Sword of Hephaestus

Hephaestus is a weapon that was forged by Hephaestus himself. Like most of Hephaestus' creations, it was made in connection to all of his other creations. It is the only thing that can pierce the Metal of Hephaestus.

Whoever uses the Sword to strike something that is forged by Hephaestus will perish after the blow.

Xena: Warrior Princess

 * "Prometheus"