Gravity wrench

From Halopedia, the Halo wiki

A fan-made image of Mister Chief created for use in Template:Realworld.
This article contains information about a non-canonical subject that, while official, is not part of the established Halo universe.
The Master Chief charging the weapon.

The gravity wrench was a deleted Covenant weapon intended for an early version of Halo: Combat Evolved. It may have also inspired the plasma pistol, as the weapon must first be charged, and then will fire a strong ball of energy. In addition to that, it appears to act like an early version of the flamethrower, or other support weapons.