Armblade Brass Knuckles +3

Push (Mastery): If you hit a creature with this weapon, you can push the creature up to 10 feet straight away from yourself if it is Large or smaller.

You have a +3 bonus to attack and damage rolls made with this weapon.

An armblade is a magic weapon that attaches to your arm, becoming inseparable from you as long as you're attuned to it. To attune to this item, you must hold it against your forearm for the entire attunement period. As a bonus action, you can retract the armblade into your forearm or extend it from there. While it is extended, you can use the weapon as if you were holding it, and you can't use that hand for other purposes.

Light: A light weapon is small and easy to handle, making it ideal for use when fighting with two weapons.

Proficiency: simple, brass knuckles Source: Dungeon Master's Guide (2014) p. 213, Eberron: Rising from the Last War p. 276, Wayfinder's Guide to Eberron p. 120, Ben Huffman - Pugilist (Third Party)