The Purgatory Blade is a weapon that is used by inhabitants of Purgatory, made from materials in the realm. Dean Winchester and Benny Lafitte are frequently seen carrying these blades in their time in Purgatory during Season 8.
It was made, rather crudely, out of materials from Purgatory, one of them being a bone. It is suggested that this blade is powerful, since it can kill dead monsters in Purgatory, and Dean thought it would be useful against demons on Earth. In the confrontation however, it had been swiped away.
It was later shown that Dean still had the blade in his possession and used to wipe out Benny's old nest, beheading at least five vampires with the blade. In flashbacks he uses it to behead a Leviathan and kill a few monsters attacking him, Castiel and Benny. Benny uses a similar blade for similar purposes. In another flashback, Dean uses the blade to decapitate two Leviathans that attack him and Castiel and carries it with him through the portal out of Purgatory.
Sam steals a similar blade from a monster during his trip to Purgatory, carrying it through Hell and back, only to offer it up to Benny as he escapes.
In Dean's hallucination of Purgatory from the Werther Box, Benny saves Dean by decapitating a Leviathan with a Purgatory Blade and offers Dean his blade to kill himself with. However, seeing through the hallucination and due to the Mark of Cain not letting him kill himself, Dean stabs Benny with the blade instead, killing him and ending the hallucination.
- Season 8