While writing FATERIP this was my idea as a possible option to use. If someone is employing a ‘garden variety’ weapon. Cheap handgun where those are commonly available, knife, blackjack, club, knuckledusters, rock etc then there is no damage bonus.
If using something out of the ordinary, like a large sword, machine gun, sniper rifle, battleaxe, electricity pole etc. then calls those Weapon: 1. Prepared intent to be nasty, if you like, as opposed to stumble into a brawl.