What are the ways my non-monk character can improve their unarmed damage?

Question

My Goliath Barbarian / Fighter / Rogue hybrid killed somebody accidentally in a rage in their past, and has sworn an oath to never again wield a weapon to prevent accidentally killing somebody again if they fly of the rails.

Problem is, this is still D&D, and punching people for 1+strength mod+2 while raging is hardly going to impress anybody. He'll primarily be a grappler, so it's not that big a deal, but I'd still like to find some ways to improve his damage.

There's a caveat however, I can't take any feats, considering my classes are spread all over the place and I need the few attribute increases I can get.

These are the requirements:

• Increases can come from magic items. I've found the Insignia of Claws in Hoard of the Dragon Queen, but that's the only one I've found so far.
• Can't change my race into something else. I know Tabaxi, for example, have improved unarmed damage, but that doesn't help my Goliath.
• Can't multiclass into monk or any other class. I just don't have the levels left to start multiclassing into a 4th class, nor would I meet the wisdom requirement.
• No feats. I know tavern brawler will increase my damage to 1d4, but I don't have room for feats in this build because of its multiclass nature.
• DM will not allow sneak attack on unarmed attacks.
• The build so far is 4 levels barbarian (Bear totem), 3 levels fighter (Battlemaster), 1 level rogue. The rest of the levels will go into fighter and barbarian, so they offer no leeway for multiclassing.
• Other people casting buffs on the character is a valid advice.
• I'll likely be grappling two people at the same time, so using 'not a weapon' improvised attacks is not an option, it's going to be kicks and headbutts.

Answer 1

If you can get your DM to allow use of Unearthed Arcana: Class Feature Variants, you can make use of Martial Versatility (replace Fighting Style with another on levelup) and Unarmed Fighting style, which works well with grappling:

Your unarmed strikes can deal bludgeoning damage equal to 1d6 + your Strength modifier. If you strike with two free hands, the d6 becomes a d8.
When you successfully start a grapple, you can deal 1d4 bludgeoning damage to the grappled creature. Until the grapple ends, you can also deal this damage to the creature whenever you hit it with a melee attack.

So, in the end you would deal d6+d4+str+rage damage to a grappled creature for 5 average damage per hit increase from what you have now.

EDIT: Unarmed Fighting was printed in the Tasha's Cauldron of Everything with one difference: instead of damaging enemy on grapple start and every hit, you instead deal automatic damage to a single creature at the beginning of your turn.

Answer 2

The simplest solution to your problem is a magic item that doesn't increase your damage, but rather increases your Strength score.

There are multiple items that can do this, most notably the Belts of Giant Strength. The legendary Belt of Storm Giant Strength will make your Strength score 29, giving you an ability modifier of +9. Additionally, the Manual of Gainful Exercise will bring up your modifier permanently.

Keep in mind that the most Belts of Giant Strength are incredibly rare, and the Manual is classified as Very Rare.

Now, another choice for you is to wield a shield. You swore to never use a weapon, but perhaps your DM will allow you to use your shield to bash people. If they feel particularly generous, they might even allow magical shields to deal extra damage based on their bonus. (Note: this is generally not allowed and would have to be run by the DM. I'm not even sure if you would count a shield as "not a weapon," but I'm just giving you an idea here).

Answer 3

You seem to be focused on damage output ("punching people for X is hardly going to impress anybody") but that mindset kind of violates the spirit of your oath. I sounds like "I want to maximize my ability to kill enemies while raging without holding a weapon."

So I would suggest an alternate mindset. I have years of experience playing wonky grapplers in various versions of DnD/PF, and the reason I did it so often is because they are both fun and incredibly effective when you shift your mindset to "controller" instead of "damage dealer"

In previous versions it was a little easier because getting an enemy grappled prevented them from attacking anybody else, but there is still enough in DnD 5e to milk the grappled condition to great effectiveness.

When you think about it, an effective grappler can usually pick one enemy and remove them from combat. Suddenly that Big bad evil guy isn't a threat to anybody else in your party. That is CRAZY effective when used well and it will drive you DM nuts once you figure out how to neuter every encounter with less than 2 big threats. (My DM started leaning heavily on swarms once he realized how I was minimizing the threat of his encounters)

In 5E, grappling removes movement from the enemy, that means you can drag them out of range from your teammates, your rogue gets free sneak-attacks, they can't dodge anything, and they are unable to stand up if knocked prone.

So just give up on damage and focus on getting your grappling score off the charts. Then waltz into the fray and take out the biggest threat, then knock them down and hold them there while the rest of your party deals with whatever is left over, then everybody gangs up on the poor sap pinned to the ground. Sure, you will get hurt in the process, but the way I see it, the casters can spend precious spell slots (a valuable commodity) to remove one creature from the fight, while a grappler gets to spend hit points (easy to replenish) to do the same thing.

From an RP point of view, this makes sense as well, you are holding down a threat and willfully absorbing injuries in order to protect your friends. You could play the guilt angle or the righteous fury angle. You don't ever finish anybody off, you always let others do that dirty deed that you are no longer capable of doing. Personally, I think that is a super interesting addition to the story and allows everybody else to play off of your character's restrictions.

Related example: the most crazily effective melee character I ever played was a 3.5 human wizard with nothing but transmutation spells. When a fight happened, he would transform himself into a large troll with flaming skin (balor nimbus) who had something like 32 strength and a +28 grapple check. He could grab and pin almost anything and would do 6d6 damage every round simply by holding onto them.

Answer 4

The alter self spell is a possibility albeit not a great one. You'd need to get access to the spell via something like a ring of spell storing. However, you can't rage and concentrate on a spell at the same time.

Another option is demon armor which turns your unarmed attacks into magical +1 weapons which do 1d8 slashing damage. Again though, it is plate armor which will interfere with certain barbarian class features, not to mention the other side effects.

Answer 5

Very few within the bounds you set.

Totem Barbarians, Battlemasters, and Rogues have no features that enhance unarmed strikes specifically. Moreover, the Insignia of Claws is the only magic item that enhances unarmed strikes specifically.

There are a couple wondrous items that could be acceptable to use within the bounds of your oath, even though they count as weapons for the purpose of making attacks: the Arcane Propulsion Arm from "Eberon: Rising from the Last War" is a prostetic limb; the Claws of the Umber Hulk from "Princes of the Apocalypse" are a pair of clawed gauntlets.

Consider changing your build

Your build is not tailored to your oath, and if you intended for this oath to be a permanent, then it would be reasonable to allow you to alter your build. It's not unheard of to let players shuffle around ability scores and/or replace class levels to suit drastic changes of character. And these changes need not be instantaneous.

For example, you might replace the barbarian levels with monk levels and shift you ability scores accordingly, or you might forgo the rogue dip if that makes room for an extra feat.

Consider a less drastic oath

This really depends on the circumstances that prompted the oath. For example, if the accidental kill was perpetrated with a heavy and sharp weapon with which it is diffucult to show restraint, then the oath could limit you to something light and blunt like a club. There are also oaths that require you to do things, like an oath to make amends to the accidental victim's family.

Answer 6

As mentioned above, there are few options within the established limitations.

It was mentioned that raising strength with a tome or the Giant belt could help. The Gauntlet of ogre power are more common though (if your strength is below 19)

The insignia of claw you mentioned. There are also a few tattoos from Tasha’s Cauldron of Everything.

The Eldritch Claw Tattoo

Magical Strikes. While the tattoo is on your skin, your unarmed strikes are considered magical for the purpose of overcoming immunity and resistance to nonmagical attacks, and you gain a +1 bonus to attack and damage rolls with unarmed strikes.

Eldritch Maul. As a bonus action, you can empower the tattoo for 1 minute. For the duration, each of your melee attacks with a weapon or an unarmed strike can reach a target up to 15 feet away from you, as inky tendrils launch toward the target. In addition, your melee attacks deal an extra 1d6 force damage on a hit. Once used, this bonus action can't be used again until the next dawn.

Coiling Grasp Tattoo

Grasping Tendrils. While the tattoo is on your skin, you can, as an action, cause the tattoo to extrude into inky tendrils, which reach for a creature you can see within 15 feet of you. The creature must succeed on a DC 14 Strength saving throw or take 3d6 force damage and be grappled by you. As an action, the creature can escape the grapple by succeeding on a DC 14 Strength (Athletics) or Dexterity (Acrobatics) check. The grapple also ends if you halt it (no action required), if the creature is ever more than 15 feet away from you, or if you use this tattoo on a different creature.

This one can allows for massive reach, which can also be optimized with opportunity attack.

Spells like Primal Savagery, Alter Self, or even polymorph can work pretty great. Enlarge/Reduce can also help you hit harder. Bless can help to hit, but not with damage.

To access spells yourself, Spellwrougth Tattoos, Spell Gems (the cool thing with this one is that you don’t have to concentrate, spell go for their full duration. The spell is actually cast and it’s the effect that is stored in the ring (unlike the other mentioned here where you have to cast yourself), so no verbal, somatic or components either (as those were already used when putting the spell into the gem) it can be more practical with a front-liner that isn’t a caster), and Ring of Spell Storing can be good option (though the first is a consumable)

There are also potions if this is not needed too often or you have a potion crafter in you group. Potion of Giant Strength, Potion of Growth, Potion of Heroism, or Potion of Giant Size.

Even more niche, and less likely to be offered by you DM are Dark Gifts from Von Richten’s Guide to Ravenloft.

The Dark Guift Second Skin Offers this

Transformation. You can cast the Alter Self spell to appear in your second form. When you do so, you gain the effects of that spell's Change Appearance option and cannot end it to gain the benefits of a different option. Casting alter self in this way requires no spell slot, and you must finish a long rest before you can cast it this way again. Your spellcasting ability for this spell is Intelligence, Wisdom, or Charisma (your choice when you gain this Dark Gift). If you have spell slots of 2nd level or higher, you can cast this spell with them.

When you cast Alter Self using this feature, some cosmetic aspect of your second form remains after the spell ends. This visibly marks you unless you actively hide or disguise it. The mark is a perceptible change such as scaly skin, stunted wings, eyes without pupils, or horns. The mark fades after you finish a long rest.

Whereas the Dark Gift Deathly Touch offer these Features.

Death Touch. You can focus your deadly touch against your foes. As an action, make one unarmed strike. On a hit, the target takes an additional 1d10 necrotic damage. This damage increases by 1d10 when you reach 5th level (2d10), 11th level (3d10), and 17th level (4d10).

Inescapable Death. When you hit a target with an attack roll and deal necrotic damage, you ignore the target's resistance to that damage.

Withering Contact. When you start your turn grappling a creature or grappled by it, the creature takes 1d10 necrotic damage.

Outside of that, there are some infusions and armours but they would probably clash with your build.

Classes, Races, and feats are generally the best way.

There are plenty of homebrew options and reskinning or tweaking of existing things. For example, Taldorei Campaign Guide Reborn has a Vestige of Divergence that are fistwrapt (Wraps of Dyamak), they require attunement by a monk, but if you change only that, you could gain between +1 ans +3 to unarmed strikes.

Lacanthropy could also be a thing.

That’s all that comes to mind at the moment.