The First Blade (Omniverse)

The First Blade is a weapon in the series Power Rangers: Omniverse

History
The First Blade is a powerful supernatural weapon, which was originally the weapon that Cain used to kill Abel. The Blade possessed the ability to kill even the most powerful demons, mostly a Knight of Hell, but it would only work when wielded while possessing the Mark of Cain.

The Mark of Cain somehow powers the blade, and when held by the bearer of the Mark, is able to kill any known being. It is also the only one of few things that could kill a Knight of Hell. It is so powerful that Crowley once called it, "the most dangerous weapon on the planet." It is dangerous enough to cause fear in even angels, which the blade can also kill.