Stop, Shoot is a gear perk that raises your weapon damage against the last enemy you hit with that weapon. It rewards focusing fire on one target at a time, which suits tough enemies.
Keep shooting the same enemy and your shots hit harder. Switching targets resets who gets the bonus.
Wear the Kyrati Cut. Gear perks are fixed to the piece of clothing that carries them, so you get this one by wearing that piece, not by unlocking it in a menu.
Good when you face a few tough targets. It does less in fights against many weak enemies.