So argument is Kitty is smart to asses that Deathstrike wouldn't be hurt but not smart enough to these Deathstrike would be hurt. There is no nuance need Kitty is maiming people not trying kill them. She knows how hurt without killing them.Either you don't like change which people are fine to have that opinion or your don't mind bad guys who are trying to kill the heroes get seriously hurt. Now if you want to waste your time trying to figure out if Kate killed imaginary henchmen go ahead there is going to be no way to ever figure that out.
I am perfectly fine that the Wolverine trained Kate Pryde is fighting more brutally, It does take much of logic leap from there and her life situation to understand her changes. It is out of her normal character but make sense with her life state and fighting background.