From playing on hard quite a bit, I have the feeling the factions AI is a lot less threatening than the monsters, in that I can usually just ignore them and concentrate on killing monsters and earning xp for my sovereign and heroes because I know they pose no threat (unless I went to far in the map to protect my realm), and then steamroll them.

I also noticed the lack of bows and skills that matter for heroes/sovereigns that choose that weapon. And it's not clear for me which stat would be more rewarding to increase to make them do more damage. Is it dex, str? For skill tech choices, is it path of the assassin? warrior? Most of the skills you get after seem to be more appropriate for a melee character than a ranged one. I tried pure mage and pure warrior sovereigns (I love playing "heroes" kind of games, and make them really powerful), and they both work really well. Mage's damage and cost of spells escalate really well, especially in large maps where you get access to several shards. And warriors get the same through skills and gear. For archers, I just don't know...

One last thing: I still could't finish a game. At some point, I just can't load my saves anymore (none of them). Maybe it's related to some quest bug, I don't know.