Sneaking doesn't work well against Deathclaws. They constantly move and turn around and their perception is super high. Unless you're using stealth boy, you will get detected most of the time.
Paralyzing palm... VATS doesn't make you immortal anymore. When fighting an Legendary deathclaw, he will take a swipe at you while you're doing VATS animation. And it instantly kills you on Very Hard.
The most optimal way to deal with Death Claws is a sniper round to the head. It will kill them instantly no matter what difficulty - it does around 460 damage with Gobi and hand crafted Ammo on V. Hard - Deathclaw has 250 HP. Slightly more with regular sniper rifle.
Legendary Deathclaw has 850 HP. Gauss Rifle with max overcharged MFCs, when hitting the head, will score a sneak hit critical doing 900+ damage on very hard, thus being the only weapon that can kill it in one hit.