Once, a long time ago, there was a setting sourcebook/adventure for the Swedish RPG Drakar och Demoner called Svavelvinter (Sulphur Winter). One of the more unique items in that adventure was a dagger called Demens. Demens was really the mind of a well-learned sage, thousands of years old, who had been trapped in the dagger as a result of a magical accident. However, most of Demens's knowledge was woefully out of date (he had been lying around in a tomb for centuries if not millenia, after all), and it was pretty useless as a weapon too. Each time you hit someone with it, there was a chance that the blade would come loose, which would result in the dagger shouting "My teef! My teef!"