What would like to know now, is a list of the most easy and hard battles. For Nightmare but also for Normal difficulty. I think overall balance should be acceptable, and of course depends on which skill/builds you have, if you buy a lot of items, etc. So again, really hard to say to judge it well
Maybe a scheme like this:
EASY
Battle XYZ bla bla. Maybe explain why. Of course, a fun thing of RPGs is finding exploits to win, but if is really something lame I should fix it
HARD
Battle XZY bla bla. Like above. If you have saves as always feel free to send them
