Is this homebrew variant of the Two Weapon Fighting feat balanced?

Question

I (the DM) am considering the following feat, after a player asked about an alternative way to use Two Weapon Fighting.

Knife Fighter

You are especially skilled at the use of the Dagger, gaining the following benefits:

• You gain a +1 bonus to AC while you are wielding a dagger.

• You can use two-weapon fighting even when the one-handed melee weapon you attack with is not light, so long as the bonus action attack is made with a dagger.

• You can additionally draw or stow a dagger when you would normally be able to draw or stow any one-handed weapon.

• You do an additional 2 damage when you hit with a dagger.

Obviously, the most direct comparison is to Dual Weilder. The intent of the feat is to allow a character to wield a Rapier and Dagger, or a pair of daggers and not be at a significant mechanical disadvantage over the Dual Wielder with a pair of rapiers.

Advantages I see compared to the Dual Wielder:

• Marginally less expensive/heavy.
• More concealable.

Disadvantages:

• Additional damage is not multiplied on a critical hit.

Are there additional issues I have missed that would make this feat better or worse than Dual Wielder? Are the issues (above or otherwise) likely to cause problems or have interactions I have not forseen?

Answer 1

I see you have taken inspiration from Dual Wielder for the final point, however I'm not a fan of the wording on this point for three reasons:

You can additionally draw or stow a dagger when you would normally be able to draw or stow any one-handed weapon

1. I find the sentence to be backward, and so a little difficult to parse.
2. The timing isn't clear, I begin the turn with a free object interaction, so I'm able to draw a weapon, I use that to "additionally" draw a dagger. Immediately after I still have my free object interaction, so I'm able to draw a weapon, can I once again "additionally" draw a dagger? It seems strange to me. On Dual Wielder you have an option that replaces drawing/stowing, it isn't "additional", so we don't have this confusion.
3. It is unusual for features in 5e to grant "free" actions. Usually, if you gain a new effect it will be attached to an existing action so that you don't have to keep track of more stuff. Dual Wielder does the same, it changes your object interaction.

I suggest the following change:

When you draw or stow any one-handed weapon, you may also draw or stow a dagger.

You should also consider your wording for:

You can use two-weapon fighting even when the one-handed melee weapon you attack with is not light, so long as the bonus attack is made with a dagger.

This lets you use TWF effects, but it stops you from attacking twice with a dagger in 1 hand and no other weapon. Consider which you think fits the feat more. It seems that TWF is what you were aiming for, so it might be best not to change it.

Consider if you need this feat

There isn't much difference between dual rapiers, and rapier with dagger, it's 2 damage. That's far from a significant mechanical disadvantage. Daggers are smaller, lighter, and you can throw them. I think that more than makes up for the roughly 6 less damage they will deal in a 3 round fight.

Your feat turns rapier/dagger into basically the same thing as rapier/rapier. Is that really what your player wants? If they want to play rapier/rapier but have one of them be actually a dagger, then just let them re-fluff one of the rapiers as a dagger. Main-gauche's look like small rapiers anyway.

If they want to get more of the flavor of rapier/dagger, then you would be better off fluffing a shield as a parrying dagger or introducing a feat/mechanics that better reflect the way that parrying daggers were actually used.

Answer 2

I see two issues with wording.

You can additionally draw or stow a dagger when you would normally be able to draw or stow any one-handed weapon.

So, if character would be able do draw a rapier, but instead they would decide to draw a wand, they still can draw a dagger. Because condition is being able to draw one-handed weapon, not actually drawing it.

I don't see it as a problem, but it looks like an unintended consequence, as you asked.

You do an additional 2 damage when you hit with a dagger.

As mentioned already this works on all hits. Throwing dagger hits. Hits with dagger used as monk weapons. And I'm not sure about the Cloud of Daggers spell. But notably it won't help with Ice Knife spell, despite the matching names.

Change it to the "You do an additional 2 damage on hit with melee attack with a dagger.", or something like this.

Answer 3

The feat is balanced but can be improved by taking inspiration from Crossbow Expert.

The feat seems balanced, in the sense that Knife Fighter wielding a dagger makes it comparable to Dual Wielder with swords. But, we can take inspiration from Crossbow Expert to make the feat more clear.

The third point of Crossbow Expert says:

When you use the Attack action and attack with a one-handed weapon, you can use a bonus action to attack with a hand crossbow you are holding.

I would model the second point of Knife Fighter after this like so:

When you use the Attack action and attack with a one-handed melee weapon, you can use a bonus action to make a melee attack with a dagger you are holding.

First, it seems this does exactly the same thing as your original wording when you are holding a rapier and a dagger, but allows you to add your ability modifier to the dagger damage, additionally, it grants the bonus action attack when your are holding a dagger and only that dagger. Much like crossbow expert for hand crossbows, this would allow one to make an Attack action attack and a bonus action attack while only holding one dagger - which seems more true to the name Knife Fighter. It would seem odd to me if Knife Fighter didn’t make you better at fighting with just one knife.

Finally, I would just reword the last point like so:

When you make a melee weapon attack with a dagger and hit, you add 2 damage to the damage roll.

I think this clarification fixes any question we might have about when it triggers.

Overall, these changes do make it a bit stronger than you originally had it written, but I think that's okay - it's still not as good as feats like Crossbow Expert, Sharpshooter, and Great Weapon Master.