When my Beast Barbarian reaches level 5, with one hand empty and the other holding a dagger, after making two claw attacks plus an extra attack, can I then use a bonus action to attack with the dagger using Two-Weapon Fighting?
Would the Dual Wielder feat be effective for the dagger attack in such a scenario?
The Two-Weapon Fighting feature requires that both weapons used for the attacks have the light property (emphases mine):
When you take the Attack action and attack with a light melee weapon that you’re holding in one hand, you can use a bonus action to attack with a different light melee weapon that you’re holding in the other hand. You don’t add your ability modifier to the damage of the bonus attack, unless that modifier is negative.
The claws of Barbarian with the Path of the Beast subclass do not have such property:
Until the rage ends, you manifest a natural weapon. It counts as a simple melee weapon for you, [...]
hence they do not qualify for using Two-Weapon fighting Bonus Action.
If your table allows using feats, the Dual Wielder feat removes the light property requirement:
You can use two-weapon fighting even when the one-handed melee weapons you are wielding aren't light.
The above features require that you have to hold and/or to wield the weapons to benefit of the advantages of such features. Since it is not clear if natural weapons are held or not, this decision is up to the DM, which should take into account that such claws count as simple melee weapons for you.
Two weapon fighting requires you to be holding two different light weapons, unless you have the dual wielder feat (which removes the light requirement).
Your claws are arguably not being held, and definitely do not have the light property.
(I would advise against taking the dual wielder feat for this, as the feat isn't great even in optimal situations. And it your claws aren't an optimal weapon to dual wield with.)
By the rules as written, you can grab yourself a two handed sword. You can make one two handed sword attack, one claw attack, and then an extra claw attack.
The potential damage done is 4d6 plus 3x your strength modifier, plus 3x rage damage. With 18 strength this is an average of 14+12+6=32, and this does not require your bonus action.
In comparison, if you treated claws as being two weapons with the light property, you could do claw, claw, beast extra claw, bonus action claw for 4d6 plus 3 times your strength modifier, plus 4x rage damage. With 18 strength this is an average of 14+12+8=34, minus 5.5 if you don't have a bonus action.
If you treated claws as being a single weapon, but held and with the light property, you could wield a short sword. Then you could do claw, sword, beast action claw, bonus action sword, for a total of 4d6 plus 3 times your strength modifier. This does the same damage as the above.
(In comparsion, a baseline 2H sword barbarian does 4d6+str x2+rage x2, or 26, and a 16 strength reckless GWM does 44 at -6 accuracy.)
If you permitted claws to be 2 different light held weapons, at level 3 you could do claw, beast claw, bonus claw, dealing 3d6+2x strength+3x rage damage (22.5).
If you treated it as a light weapon held, but only one of them, then claw, beast claw, bonus short sword deals the same damage.
Without treating them as light, we deal 2d6+2x strength+2x rage (7+6+4=17).
(In comparison, a baseline 2H sword barbarian does 2d6+strength+rage or 13.)
Reading the claws as light and held (in the hand that is free) is only a 6% increase in damage output on turns you have a bonus action free, and a reduction in damage output on turns you don't have a bonus action free of 11%. As you lack a bonus action the turn you rage, this is pretty much a wash.
At level 3, however, this technique allows a 32% increase in damage output.
What more, Path of the Beast (Claw) is already a decent damage barbarian build; it incompatible and viable competition to a GWM barbarian; the PAM+GWM VHuman is clearly higher (58.5 average damage at -6 to hit is worth it with reckless). And at level 3 it is by far one of the higher damage builds.
By RAW, you can't do this.
But at level 5, allowing this trick isn't worth ruling against as a DM, as the visuals are more fun and the balance impact is zilch.
So what I would do is allow it, and require the separate weapon. Ie, your claws are wielded, but considered the "same" weapon, so they can't TWF by themselves.
I would also only allow it at level 5 and above.
At least it shouldn't work as written, without some rules-bending, so ask your DM.
Two-Weapon Fighting requires you to hold a weapon in the hand:
you can use a bonus action to attack with a different light melee weapon that you’re holding in the other hand
Dual Wielder doesn't negate this requirement, it explicitly says you have to wield the weapon:
You can use two-weapon fighting even when the one-handed melee weapons you are wielding aren’t light.
You neither hold nor wield natural weapons — they are your body parts. See this and this for more information.
However, Form of the Beast has an interesting detail:
Until the rage ends, you manifest a natural weapon. It counts as a simple melee weapon for you
So the claw counts as a simple melee weapon, so it worth asking the DM, does this also count as "wielding".
If it does, Dual Wielder feat should allow Two-Weapon Fighting using any combination of these:
I see no problems with one extra 1d6 attack, which only works in rage.
Two-Weapon fighting says:
When you take the Attack action and attack with a light melee weapon that you’re holding in one hand,
Even though your claws count as melee weapons, and even though Dual Wielder lifts the need for these weapons to be light, you are not holding your claws in your hand.
Firstly, even if you assumed that the claws would still count as hands, you are not holding them in your hands. They are your hands then.
This is different from the question if you wield these claws as weapons, which you likely also do not, based on the common English definition (Cambridge Dictionary):
to hold a weapon or tool and look as if you are going to use it
While other games have defined wield more widely, there is no clear evidence for that in 5e. And here, it also does not matter as you do not need to wield the weapon, you explicitly need to hold the weapon in your hand.
Secondly, you don't even have hands to hold anything in any more:
Each of your hands transforms into a claw,
Your hands transformed into claws. By the time you can use the claws, they are claws, not hands. Transformed hands are as much hands as a chair that is smashed to splinters is still a chair: they aren‘t.
That said, this probably would not be game breaking, it requires investment of a feat, and there are other ways to deal a lot of damage with a barbarian, like using Great Weapon Master, Polearm Master (or both). So check with your DM if they want to allow it.
You'd have to trade one more claw attack for a light weapon attack to make this work without feats.
As others have mentioned, the claws don't count as a light weapon so on their own, they cannot enable the two-weapon fighting bonus attack.
That said, much like the trick with attacking with two-handed weapons and still getting the extra claw attack, at 5+, you can forego a claw attack of the Attack action for drawing a light weapon and attacking with that instead to enable two-weapon fighting.
So, with an empty hand and a light weapon in the other hand, your attack action would go:
That would be sufficient to allow you to take a bonus action to attack with the other light weapon, I believe.
(On turns where you start with the dagger in-hand, I guess you'd have to make the first swing with it then drop/stow it to make your claw attacks.)
