Soul-Drinker is an ancient broadsword with a malign intellect. Its blade is wicked and jagged, its pommel wrapped in what might very well be human skin, and it has a large gem that looks like an eye (and moves, looking at things around it) set into the cross-guard. When you bond with Soul-Drinker, you promise to feed it the souls of those you slay in exchange for power.
Heart-Seeking Blade: While you bear Soul-Drinker in battle, the blade gives you unparalleled skill in slaughter and death-dealing. When you attack with Soul-Drinker with the intent to kill, your Fight skill is Superb (0)
Drink Soul: When you slay a being that has a soul with Soul-Drinker, the sword drinks in that being’s soul, turning its body to ash. You can prevent Soul-Drinker from drinking a soul, but doing so requires a Will roll at Good (+3), and it angers the sword.
Stolen Life: You can drain a soul from Soul-Drinker to heal yourself. To do so, spend a fate point and make a Will roll at Good (+3). On a success, Soul-Drinker sees that your survival is in its best interests, and allows you to consume a soul. Clear out your physical stress track and choose one consequence: reduce its severity by one level (erasing it if it’s a minor consequence). If you fail the roll you may still heal as above, but Soul-Drinker revokes this ability until you perform some service for it; it will tell you what it wants.