I just got 50 unarmed skill and the option in VATS came up for uppercut. My roommate has 70ish melee weapons and he gets the option for Mauler. We have been experimenting with the mauler ability and each weapon seems to do different things. Bumper Swords knock stuff back, Rebar clubs seem to do massive damage. However, we cant really figure out what everything does. Does anyone know what these things do exactly? For unarmed, what does Uppercut do? When I use it, it doesn't seem to do anything (although im using straight unarmed. Maybe with weapons it does something different but i dont have any fist weapons.

EDIT: Just for clarification, the mauler attack does those things for the weapons (bumper sword, etc) sometimes, but not all the time. Were still trying to figure out exactly what things do

Uppercut aims for the head. You also get cross, which knocks back and usually hits the target's arms, often dropping their weapons. Also, unarmed is given special power attacks from certain NPCs.

Mauler is the same regardless of what weapon you're using. High damage, knock back/down. There's also Scrap Heap (Thermic Lance, Chainsaw and Ripper), which seems to increase damage, Fore! (9-iron) that hits the groin, one I forgot the name that aims for the head (one handed blunt weapons) and Back Slash (one handed bladed weapons), which seems to be nothing more than a fancy attack.

[e] Also note that certain animations vary based on the weapon used. Scrap Heap looks way off with Thermic Lance, but looks like you're cutting the target's privates off with the Chainsaw. Mauler's knockback is based on the animation, and can be inconsistent for certain weapons. Fire Axe/Knock Knock! and Super Sledge/Oh Baby! are very reliable in that regard, though.