Dainsleif. The weapon from Norse mythology, the dwarves were forced to craft it for a King, not appreciating that they were forced to work for him, so they cursed it. Once drawn it must kill a man before being sheathed again, and in a few decades you'd commit suicide with the sword - it never failed to kill or leave wounds which would never heal. I, Jack Miles, sixteen years old, son of Frey, somehow cheated the curse. And the dwarves are out to kill me for it.