Adamantine Brass Knuckles

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.

Whenever you hit an object with this weapon, the hit is a critical hit.

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: Xanathar's Guide to Everything p. 78, Ben Huffman - Pugilist (Third Party)