First Blade

Cain offered himself to Lucifer so that Abel would go to Heaven

Lucifer agreed, on the condition that Cain be the one to send his brother to Heaven

He fashioned a weapon out of the jawbone of a donkey, powered by the “Mark of Cain”

The mark was the seal used to imprison The Darkness;

It was transferred to Cain from Lucifer, he used the First blade to kill Abel

Capable of killing anything, however it was just a regular bone without the mark

Cain copied the Mark onto Dean Winchester, so that the hunter could kill Abaddon

It was eventually removed by Rowena, redering the blade useless & powerless