This is more of a "general" thing but - I finally finished. The final fight didn't seem as difficult as two of the underbosses but I again found that the "fade from sight" was gold. With my "hell spikes" now ramped up I was able to take out the demon of lies fairly easily. Fire off several spikes, fade, run to next room if new shields are needed, fade, find as lonely a spot as possible and repeat. I still had some 80 restore potions left too. For my next adventure, I picked up where I left off with a ranger build about halfway through the first map. I can see why warriors can do repairs - I'd have to carry two to three good bows with me otherwise.
One thing for certain, this is one long game. I want to play a sword/ax warrior as well as a stealthy rogue type so it looks like it'll be quite a while until I get to "Beyond Divinity" and Divinity II (which appears to actually be four or more games for some reason).
One last (in the wrong area) question: The Dragon Knight series; does it play much different (or at all different) from the standard Divinity series? Note that my only experience is with Divine Divinity and Original Sin (Classic).