Hey Windspin,
I can help you a little with that, but I myself don't like the idea to simply "nerf" myself so the game gets in a decent difficulty.
These are the most OP things I've seen until now:
The combination of lone wolf + glass cannon, one gives you a massive boost in HP% and the other reduces your HP% and doubles your action points, too much sinergy. I don't think either of them are OP on their own.
I didn't play it myself, but seems like level 5 sneak is broken on combat, as in, you can cheese your way through every battle.
Teleport as a low level skill was probably made to add more fun to the game, which I agree it does, but it's overpowered early on. (I would get it anyway, cause I enjoy using it)
I'm not sure how you can avoid this in a "fun" way, but level 5 man-at-arms with all the related passive traits is also OP, I have this on my "all-in takier melee".
Combos overall are sort of overpowered, but these are core to the fun of the game, you shouldn't avoid them really, this is THE thing that needs a harder difficulty to not be overpowered.
I'm sure there are plenty other things that are a little out there, like skills that put an elemental shield over your character, but I don't really know them all.
