Bleeding Weapon Fusion
(from Starfinder Core Rulebook)
The bleeding fusion weaves entropic energy into the weapon’s form. The weapon gains the bleed critical hit effect. The amount of damage taken each round from this effect is equal to 1d6 per 5 levels of the weapon, rounded down. If the weapon already has a critical hit effect, when you score a critical hit, you can apply either the weapon’s normal critical hit effect or the bleed effect. Only weapons that deal piercing or slashing damage can have this fusion.