Two-weapon fighting in D&D 2024: how dual wielding actually works
In the 2024 rules dual wielding is not a fighting style or a feat; it is the Light weapon property. When you take the Attack action and attack with a Light weapon, you can make one extra attack as a Bonus Action later the same turn with a different Light weapon, and you do not add your ability modifier to that extra attack's damage unless the modifier is negative. Everything else, the Two-Weapon Fighting style, the Dual Wielder feat and the Nick mastery, is a way to improve that one sentence. The catch is the bonus action itself, which every other class feature also wants.
· 5 min read · TerrainTale

Which weapons qualify
Only weapons with the Light property trigger the extra attack, and the extra attack must use a different Light weapon. In the 2024 Player's Handbook the Light melee weapons are the club, dagger, handaxe, light hammer, sickle, scimitar and shortsword; the hand crossbow is the Light ranged weapon. A dagger thrown counts, because it is still a Light weapon, so a rogue can stab with one and throw the other. A longsword in each hand does not qualify at all without the Dual Wielder feat, and a rapier and dagger only works one way round: the rapier is not Light, so the dagger has to be the extra attack, which means the rapier has to be the first.
Under the 2014 rules the wording was that you needed a light melee weapon in each hand and the bonus attack had to be melee too. The 2024 text drops the word melee and the two-hands framing, which is why the extra attack with a thrown dagger or handaxe is now unambiguous.
- Dagger: 1d4 piercing, Finesse, Light, Thrown 20/60. Mastery Nick.
- Scimitar: 1d6 slashing, Finesse, Light. Mastery Nick.
- Shortsword: 1d6 piercing, Finesse, Light. Mastery Vex.
- Handaxe: 1d6 slashing, Light, Thrown 20/60. Mastery Vex.
- Light hammer: 1d4 bludgeoning, Light, Thrown 20/60. Mastery Nick.
- Sickle: 1d4 slashing, Light. Mastery Nick.
The ability modifier question
The extra attack adds your attack modifier to hit as normal but not to damage. A level 1 ranger with 16 Dexterity and two shortswords deals 1d6 plus 3 with the first and a plain 1d6 with the second, about 10 damage a turn if both hit. The Two-Weapon Fighting fighting style, available to fighters, paladins and rangers, fixes that: when you make the extra attack of the Light property, you add your ability modifier to its damage. That takes the same ranger to about 13 a turn, which at low levels is more than a greatsword.
The advantage fades. At level 5 a fighter with a greatsword makes two attacks at 2d6 plus 3; the dual wielder makes two at 1d6 plus 3 and a third at 1d6 plus 3 with the style. That is 19.5 against 20 on average, with the dual wielder spending a bonus action to get there. From level 5 onward the reason to dual wield is not damage; it is masteries, and the fact that three attack rolls fish for a critical or a Sneak Attack better than two.
Nick: the mastery that gives the bonus action back
The Nick mastery, on the dagger, scimitar, sickle and light hammer, lets you make the Light property's extra attack as part of the Attack action instead of as a Bonus Action, once per turn. A level 5 fighter with a scimitar and a shortsword and Nick on the scimitar makes three attacks in the Attack action and keeps the bonus action for something else. Only a class with Weapon Mastery uses it: barbarian, fighter, paladin, ranger and rogue, each for a limited number of weapons they have chosen.
Order the attacks with Nick in mind. Nick is the mastery of the weapon you make the extra attack with, so the scimitar has to be the second, extra weapon, and the first attack has to be with a different Light weapon. Pair Nick with Vex: the shortsword's Vex gives Advantage on your next attack against the target when you hit, and the scimitar's Nick spends that Advantage in the same action. A rogue with this pair has Advantage for Sneak Attack without needing an ally next to the target, which is the main reason 2024 rogues carry a shortsword and a scimitar.
What Dual Wielder does in 2024
Dual Wielder is a General feat from level 4 with a prerequisite of Strength or Dexterity 13. It gives +1 Strength or Dexterity, lets you draw or stow two one-handed weapons when you could normally handle one, and adds a second kind of extra attack: when you take the Attack action and attack with a Light weapon, you can make one extra attack as a Bonus Action with a different weapon that is a Melee weapon without the Two-Handed property. The extra weapon no longer has to be Light, so a shortsword in one hand and a longsword or rapier in the other is legal, and you still do not add the ability modifier to the extra attack's damage unless you have the fighting style.
The 2014 feat was different in two ways that matter at the table. It gave +1 AC while you held a weapon in each hand, which the 2024 version does not, and it let both weapons be non-Light; in 2024 the first attack still has to be with a Light weapon. A 2014 character with two longswords is not a 2024 character with two longswords, and a table that mixes the books should say which text it uses before the fighter buys a second sword.
Why the bonus action is the real cost
Without Nick, the dual wielder's extra attack competes with everything else that uses a bonus action: a rogue's Cunning Action to Dash or Disengage, a barbarian's Rage on the turn it starts, a paladin's Lay on Hands or a smite spell, a ranger's Hunter's Mark, a monk's Flurry of Blows. On a turn when any of those is the better use, the second weapon does nothing. That is the design intent; the Light property's extra attack is a cheap use of a bonus action, not a free one.
On a grid the position work is the same as for any melee character, with one addition: a dual wielder who moves to a second target between the Attack action and the bonus action attack is allowed to, because movement can be broken up around actions. Two goblins 10 feet apart can each take a hit from a ranger who steps between them. The initiative tracker that shows who is still standing after the first hit makes that choice quicker than counting on paper.