fjdgshdkeavd: hm, what difficulty are you playing on? I've not yet seen a boss go down in a single blow, and I have used group style (I've not finished the game yet, though). I've also never been one-hitted by a Salamandra using Illegal Sword. I'm playing on hard; maybe it has a different effect in normal vs hard?
I definitely have seen quite a few one-hit kills using group style, though.
Side note, here's another post from a modder that claims to explain it (which I can't believe is accurate, because it implies a one-hit kill would be impossible...). Unfortunately, you have to view it as a google cache.
[url=http://webcache.googleusercontent.com/search?q=cache:0l6jGEcvQjYJ:tw1.thewitcher.com/forum/index.php%3Faction%3Dprintpage%3Btopic%3D22066.0+precise+hit+witcher&hl=en&gl=us&strip=1]http://webcache.googleusercontent.com/search?q=cache:0l6jGEcvQjYJ:tw1.thewitcher.com/forum/index.php%3Faction%3Dprintpage%3Btopic%3D22066.0+precise+hit+witcher&hl=en&gl=us&strip=1[/url]
EDIT: wait, I can totally believe that's the correct explanation! He claims that the max damage it will do is 50% of opponent's hit points, which would be two swings of the sword, and two swings can happen within a single attack animation...essentially an instant kill.
On Hard.
Yeah, if he's right, you're likely to get one attack and a kill, especially with big buffs to Precise Hit.