[Amhazair]

Just a couple of comments on the ideas so far. I'll leave the modding tricks and sprite suggestions to those that actually know something about that and focus on gameplay elements from what I can glean so far:

* High Nature and Death magic, with a bit of astral and 50% PR on your troops sounds like it could play very similar to (EA and MA) C'tis. Would be even more so if you add water (even a water random) Look for ways to differntiate. Possibly blood could provide a different angle.
* Adding water, even as a random only opens the way to the nice 'poison the whole battlefield' strategies C'tis is fond of. You'll have to decide whether the usefulness of the tactic outweighs the C'tis-copycatting or not.
* If you stick to only N/D/S/E that means quite limited magic, which has to be somehow balanced. Being powerful in those paths is one way of course. (And apparently you plan on your mages being 'pretty awesome', at least the main ones.) But would they be recuit everywhere then, or capital only? If capital only then probably you need either more diversity, or your non-capital mages have to be pretty decent too. (And E/S which I have the impression you're going for on the non-sacred mages has some good synergy. If they have a good number of paths they could be quite powerful) This would also make them less C'tissian, but I don't know whether you want a decent chunk of your battlemagic to be away from your two main paths.
* Another way to balance limited magic is by a strong troop lineup, but I don't have the impression you're going that way? Unless the sacred is absoltuely awesome.
* If the barechested fanatic indeed has no/very low protection he's quite likely to die from even one hit (assuming human-range hp) and thus never get the chance to go berserk naturally.