Here's an idea for everybody....
It would be nice if Aztec Monks, Celtic Druids, dark age Christian Holy Men, and Hebrew Rabbi, all had some sort of 'morale' effect in combat by making their stack fight better or the enemy fight a little worse. The early Republican Romans say for example that the Etruscans were often led into battle by a contingent of priests "who advanced like furies, brandishing snakes and burning torches".
Well.....maybe there is a way.....
How about giving these 'units' a defensive bombardment of say 3, with a range of zero and a rate-of-fire of one?
Now when anyone tries to attack a stack that contains any Monks/Druids/Priests, there is a chance that the attacking unit may lose a hit point before the battle starts, simulating a drop in confidence.
Currently, each 'defensive bombardment' unit can only fire once per turn, so the more Priests there then the more chances of 'firing', and so giving that particular stack an advantage, at least in defense. You could even adjust the bombardment and rate-of-fire factors to simulate the fact that some nations had more powerful Gods than others!
I can't think of a way to make this system work when attacking, but it is worth a thought.