Walter is a blunt sword-like club with multiple ridges and a back-grip

A user of Walter gains +3 to ac, and cannot benefit from a shield during this time. 

If a melee weapon attack or magical melee weapon attack targets the user of Walter, and lands within Walter's added +3 ac, the attacker will immediately be grappled. If a target is grappled this way, the user of Walter can use a reaction to enter an athletics contest with their grappled target. On a success, the user of Walter will fling the grappled target's weapon 30 feet in any direction.
Walter cannot be used to directly attack victims currently grappled by it, but can still be used to attack free targets while someone is grappled. If this occurs, any damage inflicted by Walter will be shared evenly between both targets.

Walter's grappling effect will end if the grappled attacker lets go of their weapon as a free action, succeeds in an athletics contest against the user of Walter, or has had their weapon flung 30 feet in any direction by Walter's user.

As an alternative action, Walter may be used to target a held weapon specifically and may fling that weapon 30ft in a chosen direction if they are able to break through the material armor class of the targetted weapon.

Proficiency with a Greatclub allows you to add your proficiency bonus to the attack roll for any attack you make with it.

Notes: Damage: Bludgeoning, Grappled, character with a strength score of 16 or higher, Damage, Buff, Utility, Combat, Two-Handed, Push