Splitting off of the other topic on innovations, to ask:
"If you could design your own, or got to set specifications for a designer, what would you want in a handgun?"
I'll start.
1. 1911 style triggers. Ok, that's not so much an innovation, as a recognition that JB got it right in the early 1900s and for some reason, everyone is ignoring it!
2. Barrel below the action. The farther above your hand the barrel sits, the more of a factor muzzle rise is. SO why the fuck not put the barrel on the bottom, and the recoil assembly above it?
3. Forward grip. The trigger should be maybe an inch behind the muzzle, and the grip right there. The body of the gun should lay atop your arm like a wrist rocket.