Legend tells that no one has ever pulled the Z sword from its resting place, but they never mention the name of he who placed it in the stone. Perhaps the gods, the Kaioshin, don't want you to know they banished one of their own? Or perhaps it was all part of their plan to groom the next heir to the Western Universe? All kaioshade knew at that time was the pain of being bound to a sword forged by his father, who had failed to kill the demon, Buu, and the wound from a blade he couldn't control.
It was a fate worse than banishment to Hell.
Dragonball Z fan character by Kevin Deane and myself (concept and design respectively).