Mjölnir

Mjölnir is a mythical hammer belonging to the Norse god, Thor.

Powers and Abilities
This is a powerful weapon able to kill pagan gods with a single hit, and implement that, as in accordance to lore, possesses the following:


 * Weather manipulation
 * Electrokinesis - When wielded, it can release a tremendous amount of electrical current, or charge.

What's Up, Tiger Mommy?
At some point it fell into the possession of Plutus, God of greed, who auctioned it. At the auction, he accepted the finger of the Frost Giant Ymir and 5/8 of a virgin from his fellow god Vili.

Unfortunately for Vili, he was caught in the middle of a battle between the Winchesters, and Crowley, and Beau who Crowley had bribed to join him. To kill the deity, Sam took Mjölnir from Vili, and killed Beau. Sam was about to give it back to him, when it dawned on him about the virgin remains (which came from a female banker Vili murdered). He demanded to know where Vili had gotten the 5/8's of a virgin. When Vili gave him a sheepish look, Sam angrily killed Vili with the hammer.

What became of the hammer after this is not known but it was last seen laying on the floor in the middle of Vili's remains.

Trivia

 * In Norse mythology, only beings of supernatural strength such as gods like Thor himself or jotunn have been shown to wield the hammer. However, it's unknown if that also applies in the Supernatural Universe, but Sam was able to wield it like any other hammer.