I've noticed after a few games that Hard AIs have massive crystal reserves compared to other resources. I don't mean a bit of a bonus (as they should be getting at that setting), I mean absolutely impossible to get amounts. I would take over all their cities/resources and only notice 4-5 crags and they would have several thousands crystals from it (2-3 times what I have in reserve and I have way more crags - neither of us at the point of actually spending tons of crystals on troops). As a result, if you ever reach end game, the AI will often pump out endless stream of magically enchanted units without ever running out of crystals. Is this behavior intentional? The reason I ask is that in my experience, the AI that goes for magical weapons (down the magic techs) first will often completely dominate all the other AIs (assuming they don't mess with you and get destroyed first). The balancing factor for this is suppose to be crystal income, but all the AI has practically unlimited amounts of it, so ... yeah. 

Also on the topic of crystals... Alchemist Labs... IMO, one of the worst improvement in the game (-1 crystal for 2 gildar and .5 metal), something I make sure to never ever build and to raze the moment I take over a city... yet the AI has them in all their high level cities. Is this suppose to be an AI only building?