Calamity's Grasp


 * "They never see it coming." - Gyro of the Ring

Calamity's Grasp is an epic fist-weapon. The weapon's model includes a spinning 4-sided blade hovering just above the hand that slows down and speeds up at regular intervals.

Source
This item drops from Kel'Thuzad in the 25-man version of Naxxramas.