Is the double-bladed scimitar considered a "sword"?

Question

Is the double-bladed scimitar considered a "sword" for the purpose of magic items (e.g. the Mind Blade or Vorpal Sword)?

Answer 1

Probably, ask your DM.

This seems pretty straightforward, as it has the word "scimitar" in the name, and there is certainly no rule that I am aware of that says it can't. The important thing to note here is that magic item distribution is entirely at the discretion of the DM, so naturally, it's up to the DM what sort of items you receive. It's up to the DM if one of the "magic weapon templates" can be applied to the double bladed scimitar in particular, and if it can, whether or not that item is made available to the players.

WitchsFISTS gives a somewhat more detailed answer in response to a similar question: Do scimitars and rapiers count as swords for the magic items in the 5E DMG? I think the logic of their answer applies here as well:

5e does not specify specific weapon categories beyond the name of the weapon. One could say that each different name is a different weapon type, but that would mean that shortswords were a different weapon type than longswords or greatswords.

Because of this, I believe it makes much mores sense to consider that by the type "sword" for these magical items they mean any type of sword using the real world definitions for what a "sword" is, making both scimitars and Rapiers fall under that definition and therefore count as the "sword" type when dealing with magical items.

One final note, it must be mentioned that I would find it highly unusual if Valenar arcanists were not aware of the enchantments that may be applied to more pedestrian weaponry, and there is no reason to believe having put two blades onto one handle would then present an insurmountable challenge to any ambitious Valenar enchanter.

Answer 2

I did not find a definition of a "sword" in D&D 5e, so we have to resort to real world definition, which is something like a weapon with a long, sharp metal blade and a handle. I think the The important bit here is "a blade".

Description of Double-Bladed Scimitar says:

A haft of fine wood supports a long, curving blade on either end. Forged with techniques honed over centuries, these blades are strong, sharp, and remarkably light. Each scimitar is a masterpiece, and as a result the double-bladed scimitar is an expensive weapon [...]

A weapon with this description certainly has nothing to do with swords as far its appearance or use goes. Trying to use one as a sword would only result in quick self-evisceration. It's use is probably more akin to a quarterstaff, where you would try to hit the enemy with either end while not bludgeoning yourself.

However, the blades are described as being scimitar blades. Rule of Cool almost mandates, that the blades could have individual, possibly different enchantment. So the blades could certainly be considered as two swords for the purposes of your question.

I would not allow the whole weapon to be enchanted as if it was a sword. The important balance point to consider here is comparison with two-weapon fighting. Double-bladed scimitar gives one additional bonus action attack "for free" from a single two-handed weapon. If you add magic to this, the cost should be similar to having two magical weapons. So, your two particular examples:

• "The mind blade is a magic weapon that deals an extra 2d6 psychic damage to any target it hits" is what Volo's Guide to Monster's says under mind flayers. Adding one extra attack with 2d6 psychic damage is a lot. If you use the monster-as-written, it shouldn't work, because the weapon isn't a sword and it will increase the power of the monster. But rules-as-written, DM can alter the monster stat block to allow this. It will not increase CR of the Mind Flayer, but it might be enough to increase CR of who/what ever is using the Mind Blade.
• The Vorpal Sword is a legendary magic item, a +3 sword with insta-kill chance. DnDBeyond entry explicitly lists 3 swords, including scimitar, but not double-bladed scimitar, but DMG only says swords that can do slashing damage are valid base items. Still, as I explained above, two swords joined together is not a sword. Should DM still allow a vorpal double-bladed scimitar, its value/cost should probably be about the same as two "regular" vorpal scimitars, give or take, because the power would be the same.

Answer 3

Mechanically, Probably. Balance wise, could be risky.

While I think by the naming convention, and the weapon's description, it's probably a sword; however, if you want it to be a magic item, I would recommend having each blade be a separate weapon for balance.

By base, a double-bladed scimitar costs 100gp and does, before bonuses between 2-8 damage without use of your bonus action, 3-12 with. Compare this to 2 scimitars, costing 50gp, dealing between 1-6 with just your action, 2-12 with BA included. This means on average, regardless of mods, the double bladed scimitar already does more damage than just wielding 2 scimitars, at the cost of finesse and twice the price. This makes some degree of sense, especially when you factor in that in most settings, the double-blades are rare; however, when referencing magical scimitars and double-bladed scimitars this cost analysis changes wildly if you use it as one weapon. Ultimately this depends heavily on how you value magic items. If you want flat gold value, we go by DMG, as opposed to the many homebrew pricing systems, a +1 weapon could put you back anywhere from 100 gp to 500 gp regardless of the weapon, or by XGE 300-700gp for each weapon. This means 2 scimitars, the worse weapon option (2-7/4-14 vs 3-9/5-14) is now 300 gold more expensive, at least.

As Thomas pointed out, this might not be too different balance-wise from giving a Crossbow Expert a magic hand crossbow, or a Polearm Master a magic glaive. In my opinion, the biggest balance differences are:

1. OP's Question. We're looking at the Weapon (any sword) Magic items. Of the 14 magic items that category includes, excluding typing-based bonuses, such as the Slayer weapons and Holy Avenger, and ignoring chance based effects, just under 1/3 that provide a dice amount or flat bonus to damage on hit, things that are by default not allowed to be glaives or hand crossbows.
2. Crossbow Expert and Polearm Master are feats, requiring a relatively permanent player decision spec into in place of an ASI, versus this being pure GM determined loot and/or gold amounts.

Lets go back to the 2 scimitars versus 1 double-bladed as magic items.

If we look at one of the simpler extra damage items, the flame tongue sword, it's rare, and grants 2d6 extra damage on hit, with no attack bonus mod. For 2 Scimitars, this means 4,200-40,200 gp (XGE) or 1,000-10,000 gp (DMG) for 3-18/6-36 damage. 1 double-bladed scimitar is only 2,100-20,100 (XGE) or 500-5,000 gp (DMG) for 5-20/8-36.

Now, for a +2 weapon version of this, the prices are the same almost across the board. The glaive will be same price for a scimitar, the hand crossbow, assuming either a pair of them, or a one-handed +2 weapon to pair it with is the same as the double-bladed.

Glaive +2 with PAM 3-12/6-18 2 Hand Crossbow +2 w/ CBE n/a/6-16 2 Scimitars +2 3-8/6-16 Double-Bladed +2 4-10/7-16

So while yes, this ends up the on par with those builds, one could argue that's the issue. It does the exact same average damage with no such feat or permanent character decision beyond the potential story implications depending on setting of having a double-bladed scimitar in the first place.

Again, it might be risky, it's something to keep in mind. If the party's dual wielder is having to build specifically to keep up with you and spend twice as much, or aside from range, you're on par with the PAM fighter in the group, or the CBE, there might be an issue with balance.