Hmm, I'm not a real "hard RPG gamer", but I hadn't problems on "Easy" with this game!
For me is Risen more difficult!
I think it's a case about "my kind of playing a game"!
But what I can say for sure (for me!) : Divinity II has a very
intuitive controller-system (I only played on Xbox),
In other words: I was learning really FAST how to play D II with the gamepad!
And with Risen I have more problems and with Oblivion I haven't problems, it's also (for me) very intuitive to control my hero(in), but most of all intuitive in Divinity II
So I think this is, like many things in life, a personal thing!
Now I play Divinity II on "High" difficulty and since I almost kill every enemy in Brocken Valley (except the "Killer Bunny" and going to the Maxos Temple

), I haven't problems with all of this!
I think it's important in Divinity II to
explore everywhere you can to find (all) hidden area's and do all Quests you can find, Mindread for sure the most important NPC's & Enemies!
Like Raze said: level 31 to finisch is (a little bit) low! I can understand you have much trouble with the final battle!
I wish you all the best with your next hero(in) in Divinity II : Ego Draconis !!