D&D 5E Unintended consequences from knife-throwing feature?

[BluejayJunior]

Just change the wording to, "When you throw a dagger on your turn...". That will eliminate it being used for opportunity attacks, if that is something you don't want.
Also, it won't change anything for attacking a prone target because the prone condition doesn't specify melee/ranged. It says that attacks within 5 ft have advantage and if they're further then it's disadvantage. So even a melee attack with a reach weapon at 10 ft would be at disadvantage.

 

[Fenris-77]

It might be easier to just reword Crossbow Master, which already allows ranged attacks w/in 5 feet without disadvantage. Just change the additional BA from hand crossbow to dagger and you're pretty much set. Personally, I'd rather leave it a ranged attack and continue to be able to use Archery style and sharpshooter. Maybe toss in allowing sneak attack at range, which is the only reason I can think of for people going melee over range with a dagger.

 

[RSIxidor]

If you really want it to work with stuff that would normally only work with melee, just let the character have 20' reach with daggers on their turn (but they still have to throw the thing).

But I think the above is the most correct in that giving the "no disadvantage attacking within 5 feet" part of crossbow mastery is really the most elegant solution. This removes the ability to shove (you couldn't grapple anyway, that requires a free hand with the same reach) but that isn't really the worst loss. Plus, you could just say they can do it as a feature as well.