From Halopedia, the Halo wiki
The Grinder is a named variant of the T-2 EW/H, upgraded to conjure a powerful, EMP-capable gravimetric vortex from the point of impact. It uses the T-2 EW/H's model albeit with various changes to the coloring, including the head carrying a white color broken up by yellow and red stripes, and the rest of the weapon also having a red color scheme.
Halo 5: Guardians
The Grinder appears as a Level 5 Ultra Rare REQ variant of the Gravity Hammer. Contrary to its in-game description, the Grinder is actually an advanced Gravity Hammer that spawns a powerful gravimetric vortex when swung. This vortex has an EMP effect that lasts 3.45 seconds and a large kill radius of 9.9 meters. This enables the Grinder to be an effective weapon against groups of enemies and bosses, as well as an anti-vehicle weapon, although it cannot prevent splatters from vehicles, requiring the Grinder's user to boost to the side to avoid dying.
Changes from the Type-2 Energy Weapon/Hammer
Halo 5: Guardians REQ cards
List of appearances