Bone of Thrym

This weapon was forged after Thor has battled with Thrym (King of Frost Giants). Thrym had stolen Mjollnir and when Thor retrieve it (disguised like Freyja... That's another story which made Thor pissed off) he had killed all the Giants. The battle was bloody and messy. Thor had beaten Thrym pretty badly that pieces of him were scattered about.

One piece was a finger. This finger was picked up by Loki were he took it back to Asgard and he made the bone from it into a knife/wand.

The wand has the ability to cast any ice/cold spell to the users level. Also if the wand is used as a knife (piercing) and Crits the target will turn into Ice.