Gravity hammer

From Halopedia, the Halo wiki

Summary

The Gravity Hammer is the personal weapon of the Brute Chieftain, Tartarus. His is known as the Fist of Rukt. It not only serves as an excellent melee weapon, but can alter gravity to move objects and living beings around. It may contain shards from the mysterious crystal found in the book Halo: First Strike, as the crystal could alter gravity.