That honestly amazes me. I'm no whiz with these games, nor am I an exploiter or cheater, but even hard difficulty is sometimes too easy for me. There's only been a handful of fights which have caused me problems:
Other than that, I've found combats to mostly require some good use of abilities, some tactical thinking, and the ability to adapt.
Didn't you also put a fair bit of research into your character though, in order to properly min/max it?