How does the double-bladed scimitar compare to using two weapons with the Dual Wielder feat and Two-Weapon Fighting fighting style?

Question

I've often felt that having a consistent bonus-action attack (or other mechanic) is 'optimal' in builds during combat. The more actions/options you have, the 'better' you are able to handle different situations or deal more damage.

Traditionally, in order to have a consistent bonus-action attack, the Dual Wielder feat and Two-Weapon Fighting fighting style was a common source for melee-focused builds. But there was a pretty big investment in doing so (feat and fighting style).

Eberron's new double-bladed scimitar seems to bypass this investment, but does it actually? Is it better or worse from an optimization and damage output perspective?

A double-bladed scimitar is a martial weapon, weighing 6 pounds and dealing 2d4 slashing damage on a hit.

It has the two-handed property and the following special property:

• If you attack with a double-bladed scimitar as part of the Attack action on your turn, you can use a bonus action immediately after to make a melee attack with it. This attack deals 1d4 slashing damage on a hit, instead of 2d4.

Another thing to consider is the similarity of the scimitar to that of the scimitar of speed, but without the +2 property.

Answer 1

The Double-Bladed Scimitar compares very favorably to most kinds of Two-Weapon Fighting in terms of raw damage

I've created a table below of the expected DPR (damage per round) values for four different combat styles

1. Using a Double-Bladed Scimitar
2. Using a Double-Bladed Scimitar with the Great Weapon Fighting fighting style
   • The Scimitar is a two-handed weapon, and is valid for that fighting style
3. Using Shortswords for Two-Weapon Fighting
4. Using Longswords for Two-Weapon Fighting with the Dual Wielder feat

Name	AC 0	AC 11	AC 13	AC 15	AC 17	AC 20	AC 25
Scimitar x1 & off	13.200	10.500	9.150	7.800	6.450	4.425	1.050
Scimitar w/GWF x1 & off	14.700	11.700	10.200	8.700	7.200	4.950	1.200
Shortswords x1 & off	12.700	10.100	8.800	7.500	6.200	4.250	1.000
Longswords x1 & off	14.700	11.700	10.200	8.700	7.200	4.950	1.200
Scimitar x2 & off	23.900	21.450	19.000	16.550	14.100	10.425	4.300
Scimitar w/GWF x2 & off	26.400	23.700	21.000	18.300	15.600	11.550	4.800
Shortswords x2 & off	21.900	19.650	17.400	15.150	12.900	9.525	3.900
Longswords x2 & off	24.900	22.350	19.800	17.250	14.700	10.875	4.500
Scimitar x3 & off	32.700	32.700	29.350	26.000	22.650	17.625	9.250
Scimitar w/GWF x3 & off	36.200	36.200	32.500	28.800	25.100	19.550	10.300
Shortswords x3 & off	29.200	29.200	26.200	23.200	20.200	15.700	8.200
Longswords x3 & off	33.200	33.200	29.800	26.400	23.000	17.900	9.400
Scimitar x4 & off	46.250	46.250	46.250	41.500	36.750	29.625	17.750
Scimitar w/GWF x4 & off	50.750	50.750	50.750	45.550	40.350	35.550	19.550
Shortswords x4 & off	41.250	41.250	41.250	37.000	32.750	26.375	15.750
Longswords x4 & off	46.250	46.250	46.250	41.500	36.750	29.625	17.750

^{Double-Bladed Scimitar has been shortened to Scimitar due to formatting issues.}

A few important observations stand out:

• A GWF-boosted DB Scimitar will always be the best option, even if at low level when it's merely tied with Dual-Wielding Longswords (which itself required investment in a feat)
• A non-GWF-boosted DB Scimitar will be better than Shortswords, but worse than Longswords (... until level 20, where they become equal).

But it might be difficult to find its real use case

It's worth contextualizing these options. The ability to change fighting styles is still limited to the Class Features Unearthed Arcana, and Strength-based Two-Weapon Fighting characters are somewhat rare, given that Strength-based characters would generally prefer the (DPR-superior) great weapons instead, and Dexterity allows use of Rapiers with no loss in DPR compared to Longswords. As a result, for most characters that would consider using this weapon, I don't think they would likely have the GWF fighting style, so I don't think it's totally accurate to use GWF-Boosted DB Scimitar as the baseline we compare against.

So if we take as a given that most Dual-Wielding characters are Dexterity-based (invalidating use of this weapon), and most Strength-based characters would instead prefer using a Greatsword or Greataxe, the actual use-case for a weapon like this (which cannot be used with Dexterity and cannot be used with Great Weapon Mastery) is actually quite narrow.

Which leads me to the surprising conclusion that I think this weapon is... fine? Yes, it absolutely is a strict upgrade over TWF-styled weapons in the specific scenario where the person considering using this weapon is a Strength-based Fighter that did not take GWF, but I think that that type of character is actually quite rare.

Answer 2

Equal DPR without the feat, better once you get Extra Attack

For simplicity sake I'll ignore chance to hit because it is equal between the two and only deal with average damage assuming all hit. I'll also have both build use the same Strength modifier, \$S\$.

Without Extra Attack

With two-weapon fighting let's assume a build that has the two-weapon fighting style, Dual Wielder feat, and uses two longswords. Their average damage is then: $$2d8 + 2S = 9+2S$$

The Double-bladed scimitar build will only need the Great Weapon Fighting (GWF) fighting style and of course the double bladed scimitar. It makes its normal (2d4) attack and the bonus action (1d4) attack for a total average damage of: $$3d4 + 2S = 7.5 + 2S$$ Except we haven't factored in the rerolling from GWF which, if you always reroll a 1 and 2, makes the average of a \$d4 = 3\$. The total average is then: $$3d4 + 2S = 9 + 2S$$

And the two are equal, except that the Double-bladed scimitar build doesn't need to invest a feat.

With Extra attack

Once extra attack is added, things change for the worse (or better, depending on your outlook). The two-weapon build makes one extra 1d8 attack, while the scimitar build makes another 2d4 attack. In the resulting damage averages $$\text{Two-weapon} = 3d8 + 3S = 13.5 + 3S$$ $$\text{DB-Scimitar} = 5d4 + 3S = 15 + 3S$$ we can see that the scimitar build has more damage and less investment. Do note for any build that (at least for non-Eberron adventures) availability or even existence of the Double-bladed scimitar is in the hands of the DM.

Answer 3

The double bladed scimitar is significantly better than un-enhanced two-weapon fighting (the combat move, not the fighting style), slightly better than the Two Weapon Fighting fighting style alone, and arguably better than the Dual Wielder feat alone, but completely outclassed by the classic TWF+Dual Wielder combo (unless you spend a feat on your double scimitar as well). On a cost-for-cost basis, it's the best weapon available, but not so good that it makes every other choice pointless.

For the purpose of comparison, I'll assume both attack rolls hit, and I'll refer to the "Two Weapon Fighting" fighting style as "TWF" to distinguish it from the two-weapon fighting combat option.

When you use the two weapon fighting combat move alone, both weapons must be light, and the second weapon does not add a positive ability modifier to the damage; but the double-scimitar doesn't suffer from that drawback because attacking with the second blade is a special ability of the weapon and not the "two weapon fighting" combat move.

Double Bladed Scimitar: 2d4+STR + 1d4+STR = 7.5+(2*STR) damage

Unenhanced two-weapon fighting (twin shortswords, or similar weapon pair): 1d6+STR + 1d6 = 7+STR damage

TWF fighting style alone (twin scimitars): 1d6+STR + 1d6+STR = 7+(2*STR) damage

Dual Wielder feat alone (twin longswords, or similar weapon pair): 1d8+STR + 1d8 = 9+STR damage (and +1 AC)

Based on this comparison, the DBS is better than TWF by only half a point of damage, and Dual Wielder gives slightly superior damage at very low ability bonuses, but once you're at +3 or higher, the double-bladed scimitar is superior. However, taking the AC bonus into consideration, the feat might still be more desirable even at a +5 ability bonus (17.5 damage for the DBS versus 14 and +1 AC for twin longswords).

But of course, the combination of the two completely blows away every other option:

TWF fighting style + Dual Wielder feat (twin longswords): 1d8+STR + 1d8+STR = 9+(2*STR) (and +1 AC)

At a +5 Strength modifier, your damage totals would look like this: DBS = 17.5 damage Dual Wielder = 14 damage, +1 AC TWF = 17 damage TWF + Dual Wielder = 19 damage, +1 AC

As you gain levels

When you get Extra Attack, you want your primary weapon to be as damaging as possible, so the scimitar (with 5 average damage from dice) pulls very slightly ahead of the dual-wielding options (at 4.5 average damage from dice), but the difference isn't enough to really change anything that much.

But what about Revenant Blade?

You didn't mention it, but the Revenant Blade feat is essentially the Dual Wielder for the Double-Bladed Scimitar, and while it doesn't increase the damage output, it does add the +1 AC you'd get from Dual Wielder. The DBS with Revenant Blade is significantly better than Dual Wielder or TWF alone, but not as good as their combination.

But what about magic weapons?

This calculation changes slightly if you include magic weapons, because a single magical Double Bladed Scimitar counts for both blades, while a single magical weapon only counts for one hand of the two-weapon fighter.

However, that throws so many variables into the scenario that it's hard to compare. In general, a single magical DBS is better than any of the two-weapon scenarios with only one magical weapon, but the two-weapon guy has an extra "slot" to potentially use for interesting magic weapons, so that depends on how rare magic weapons are in your game, and which specific item you're eyeing. A Flametongue Double-Bladed Scimitar would be pretty devastating, but your DM might (entirely fairly) rule that the flames only affect one end of it or something of that nature.

Other Fighting Styles

Since you don't need TWF, other fighting style options are open to you. The Ranger can only really use Defensive with it, but if you're a Fighter, the Great Weapon Fighting style is so good with the DBS that it may well be broken. Your DM might decide to limit the benefit of Great Weapon Fighting to only the primary end of the weapon, or declare that it simply doesn't work with a weapon that, while two-handed, is not a classic 'great weapon'.

Final Analysis

The DBS is pretty solidly superior to any other option for the cost, if using your bonus action for extra attacks is your thing, but on the other hand, it's not so superior as to totally obviate every other option. It's only a few points of damage better than other choices, so if you want to use something else, feel free.

Also, remember that the DBS has a significant RP drawback for non-elves. Only an elf can use the weapon without question, and they lack a bonus to Strength; other races will need to win such a weapon by approbation of the elves, which may not be an easy task, or face retribution.