Mike, that would be a rather extreme case.
Spear hand or ridge hand to the v of the throat, right below the Adam's apple; finger or thumb gouge to the eyes; anything that prompts a gag or flinch reflex, and takes the person's mind off control of their balance, let alone their weapon. That's what I mean by taking their mind.
Think of the target zone as going from between the eyes, down along the spinal column through the upper torso... it's actually not so different from the ideal places to put bullets. Attack that line while simultaneously going for the weapon.