Skyrim Vanilla Melee Combat and Killmove Tests and Exploration
Sorry for the bad audio. I didn't have my audio settings right.
Maces decapitate from the front
Dual Daggers/Swords/Axes have a chance to decapitate from the front using both, or just one (Solo as well for one of course)
Decapitations are chance-based insta-kills
Backstabs are chance-based insta-kills (only daggers, swords, & greatswords backstab)
Throat slits can be performed from the sides & while in motion
You can throat slit regardless of whether your left hand is free or not
Frontal insta-stealth kills are possible undetected (like Tenchu)
You can insta-kill an alerted enemy so long as they don't detect you
Low health (I think 25%) guarantees a killmove on the last enemy who detects you, meaning you can killmove everyone so long as you're undetected (like Tenchu)
Shadow Warrior (combat cancellation master Sneak perk) isn't ideal at the closest range, but is doable, and workable into a killmove