The Sword of Madness
From ShireWiki
The Sword of Madness: Forged either by or for the God Loki; the sword has the ability to drive its wielder to the edge of insanity, yet never fully drive them mad. It is said that some of the greatest prophets, oracles and men of wisdom throughout history have possessed this Sword.
See also: Loki, Religion, Brrapa Lu'Eraro