The wrench is T-Bone's melee weapon of choice, the secondary other being his taser. It is shown as a large fixed-length wrench that Kenny holds on the front of his backpack through a series of buckles. Kenney uses the wrench to disarm and injure individuals. It can also be used in stealthy takedowns to silently knock out one's target. He can also use it in combination with his Taser: using the wrench to grab the enemy from behind (by their throat) and then jamming the Taser into their chest.
The Enforcer Combat Takedown skill is already unlocked for Ray, possibly because his wrench is heavier and hits harder than Aiden's baton.