A battle knife (or "long knife") is a thrusting weapon that has the length of a shortsword but heft and balance closer to a dagger. Typically, battle knives have thin blades, designed to pierce gaps in an opponent's armor. There is a variant, known as a "bolo knife" that has a wider blade and is used to slash rather than pierce.

A well-made battle knife is classified as a Tiny weapon, and requires an Exotic proficiency to use properly. A trained wielder uses DEX to determine melee chance to hit and damage, and adds DEX bonus to damage when used as a ranged weapon.

Battle knives that are not at least Superior in quality OR are being used by non-proficienct characters are treated as Small weapons and do not receive the dexterity-based attack and damage, instead using STR as normal.