Instead of helping him, you can just kill Butch (or watch him get killed by radroaches, but that's unlikely) and then loot his jacket.Once they're all dead, Butch will reward you with his outfit.
To repair it you need another Tunnel Snake outfit or a merchant. Used by the Tunnel Snakes gang in Vault 101, it provides a damage resistance of 4 and a bonus of 5 to Melee Weapons. It is a leather jacket with a snake emblem on the back, worn on top of a Vault 101 jumpsuit.
The Tunnel Snake outfit is a piece of clothing in Fallout 3.
