Ok, I know this is flogging a dead horse, but I really can't get past the fact that each attribute only governs 1 thing. It's just too darn simple...
Strength - beefs up your attack damage. That's it. What about giving minimum strength requirements to weapons & armor? Doesn't make sense that somebody with a 5 strength can run around wearing plate armor and swinging a war hammer. Even pure spell-casting champions can use the best weapons & armor, granted not as effectively as a warrior champion but they can still use them.
Wisdom - governs max essence. Shit, wisdom even disappears after the game starts. What about letting wisdom govern magical resistance? I can see a unit's defense value being used against some spells, like if a spell throws an actual, physical object (like a rock or bolt of ice) at somebody, their armor should be taken into account. But spells like mind blast? What's armor going to do vs that? Spell damage could be divided into physical or (arcane, meta, non-physical, magical, whatever else you can come up with), let defense play into the 'physical' spells, let magical resistance play into the others.
Intelligence - I still don't like the idea that intelligence determins how much damage a spell does. I'd rather see it govern whether or not a spell cast actually is cast, or if it fails. Right now, spells don't fail at all. They may not do any damage, but the casting always succeeds. Intelligence could also determing how many enchantments one could have going at once, or how many summoned units you can control at once, etc. You get the idea...
Charisma - Reduced cost in recruiting champs. Good, but what about getting diplomatic bonuses/penalties for high/low charisma? How about prestige bonuses to your cities? I'd think a highly charismatic leader would attract more people than a leader who is just 'blah'. Maybe an increased chance that children married off to other factions or their kids may return to your kingdom?
Dexterity - Definitely should give bonuses to defense, but it doesn't unless you're already wearing some kind of armor. Maybe a high dex could give additional bonuses when defending against missile attacks? Maybe it could help govern your combat speed, instead of combat speed being its own 'attribute'.
Also, hp's, mana, and essence... I believe those are a bit too simple as well. What about letting strength play a part in determining hp's. After all, a body packed with hard muscle should be able to take more damage than a toothpick body. So how about letting hp's be determined by something like (2con + str) / 3, so con is still the major factor, but str has it's part. Essence(or mana) could be (2wis + int) / 3, etc. You get the idea...
Thoughts?