What might be the downside of taking the Dueling fighting style over Great Weapon Fighting?

Question

Taken from the Player's Handbook - Fighter's Fighting Styles (p. 72)

Dueling When you are wielding a melee weapon in one hand and no other weapons, you gain a +2 bonus to damage rolls with that weapon.

Great Weapon Fighting When you roll a 1 or 2 on a damage die for an attack you make with a melee weapon that you are wielding with two hands, you can reroll the die and must use the new roll, even if the new roll is a 1 or a 2. The weapon must have the two-handed or versatile property for you to gain this benefit.

When wielding a versatile weapon, is there any benefit/downside to taking Duelling Over Great Weapon Fighting? Are you required to take Great Weapon Fighting when you are using a 2-handed weapon?

Answer 1

If you are using a versatile weapon, you can only gain the benefit of the Great Weapon Fighting Style if you you are using it in both hands. Similarly, you can only gain the benefit of the Dueling Fighting Style if you are using it in one hand. (And holding no other weapons.)

So, let's take a look at how this breaks down with a longsword (or battleaxe, they're equivalent.)

• 2-handed: 1d10 + Str, reroll 1s and 2s. Average damage = 6.3 + Str
• 1-handed: 1d8 + Str + 2. Average damage = 6.5 + Str.

Obligatory anydice link: http://anydice.com/program/5b1e.

As well as this, wielding your weapon 1-handed allows you to use your other hand for something. (Like a shield!) This can be a huge benefit.

So for versatile weapons, the Dueling Fighting Style is actually strictly superior to the Great Weapon Fighting Style.

However, if you want to use a two-handed weapon, you should probably use an actual two-handed weapon rather than a versatile one, at which point you can achieve much higher damage.