Disfigurer is a dane-axe which is obtained as loot when you defeat the "giants" from the quest Monsters in the Marsh who are behind the disappearing people in the Marsh.
In-game description[]
This unreasonable large Dane-Axe is almost unwieldable by a normal person, not surprising since you took it off Bergr, one of the monstrous brothers terrorising the Marsh in Ribe.