Pirates often carry long brass knives for working aboard a ship. Though brass doesn’t hold as sharp an edge as steel, it isn’t vulnerable to rust like steel is. In a pinch, a pirate can use his brass knife as a weapon. Mostly, though, they are used for cutting ropes, cleaning fish, and other sundry tasks.
A brass knife has the fragile quality. A fragile weapon gains the broken condition if the wielder rolls a natural 1 on an attack roll with the weapon. If a fragile weapon is already broken, rolling a natural 1 destroys it instead.