These close combat weapons are designed to fit comfortably around the knuckles, narrowing the contact area and therefore magnifying the amount of force delivered by a punch.
Benefit: Brass knuckles allow you to deal lethal damage.
Drawback: You may hold, but not wield, a weapon or other object in a hand wearing brass knuckles. You may cast a spell with a somatic component while wearing brass knuckles if you make a concentration check (DC 10 + the level of the spell you’re casting).
Note: Monks are proficient with brass knuckles.