Having a hand slot signature is tricky. Every class has things to do with the hands. Having a hand slot -weapon- signature is even trickier, because throughout a campaign, it’s eventually going to compete with two-handed or really good one-handed weapons. Daniela has a signature that plays really well with her initial ability… But can’t coexist with chainsaw or sledgehammer, the apex damage options in Survivor. Sure, you can run toolbelt, but that competes with old coat(1), which is four soak for one XP and an action. (Bandolier could help hold your weapons, but it can’t hold your signature; It also fights for the body slot, and Daniela can’t upgrade because she levels into survivor.)
Tinker solves this problem masterfully. It attaches to either the weapons or your wrench, whichever comes first. It cost zero XP, a single resource and no actions. Previously, the wrench was a last resort weapon (+2 to hit and two conditional damage is rapidly outpaced by other options). Now, you can use the wrench as flexibly as you always wanted: presumably to taunt Enemies off the cluever, Aloof 1HP enemies in zero actions.