Book of Vile Darkness 3.5
By Monte Cook
Every time this weapon deals damage to a creature with blood, it gains 1 blood point. When the weapon has 5 blood points, it can deal an additional 1 point of damage at the users behest (spending the blood points).
The weapon can store up to 50 blood points, allowing an additional 10 points of damage, usable all at once or divided up over a number of attacks.