cjrgreen: I understand your point, but I'm trying to come up with the enemies that could be one-hitting you on Normal. Normal should be playing the way you are requesting: fight reasonably well, you'll prevail; make a mistake in combat, you get hammered.
The patches make the game easier at the outset; have you been keeping up with the patches?
Another possibility is that the game does not get enough frame rate on your system; this makes it harder to control Geralt in combat.
I'd like to be able to make the odd mistake in combat because that's only natural, I'm not particularly skilled so it's going to happen and I'd like to learn my lesson by seeing my HP tanking as opposed to reloading.
As to what's killing me in one shot it's Nekker Warriors, Endryaga Warriors and Wraiths, Nekkers and Wraiths doing so outright, Endryaga via the combination of initial damage and poison. Those are the only enemies I've actually encountered since ramping up the difficulty and I'm facing most of them in numbers of around a dozen or so at once. I don't know if I've wandered off path and am facing them too early, I'm level 6 at the moment but it doesn't seem like there's anywhere else to go for now.