The current Execute does not feel good to me, it's a pistol "Snipe" feat that you're supposed to use in addition to Aimed Shot, but it's just not that strong after the nerfs if you use firearm pistols, I feel it's only used for making meme screenshots, of very lucky shots doing high damage to one target... requiring luck to crit, a stun/incap that goes on cooldown, having to wait 5 turns for the ability to reload...
Thinking about what if its requirements were just to be at melee range and have accuracy to target of 90-95% (synergize with laser pointer / neo luger frame / good lighting) and the cooldown was just 2-3 turns, you'd finally have something like Snipe that was reliable and could be used a lot more often in a fight with the right build, stuns would still work the same way as they'd help you get 95% accuracy.
This would be a mainstay rather than something that has 5 turn cooldown and also tied to the long cooldowns associated with stuns and incapacitations.
Yes I know it isn't as Execute-like anymore that way, but it would fix some things.