Chainfist (5e Equipment)
From D&D Wiki
Simple Melee Weapons
Some psycho thought that ultra fist users weren't killing things fast enough by punching them, so he had the great idea to make the gauntlets bigger and heavier and add on some rapidly rotating chainsaw blades. The result was the chainfist, a weapon as awesomely manly as it is terrifying.
A chainfist runs for two hours on a single energy cell.
Special. Chainfists, if worn on both hands, count as medium partial armor, granting you a +2 bonus to AC. Partial armor only grants its AC bonus if you are wearing light or no armor. If you are wearing only one piece of partial armor, you are still considered to be wearing your base armor type (e.g. no armor or light armor). Otherwise the heaviest type of partial armor you are wearing is considered to be the type are wearing (e.g. medium or heavy armor).