This may be almost heresey to say on this board, but I daresay the hero promotion is too powerful, or at least could be made more realistic.
I built Bambur very early on after rushing to Arete. I then let him sit and simmer in my capital quietly for 100 turns, promoted him up, and after the proverbial oven timer went *ding* Presto! A juggernaut who romps about the map at will!
I dont know, there is just something bizzare in the visualization: Bambur with his feet up, drinking Ale and eating Cool Ranch Doritos while racking up XP in the comfort of his private citadel.
Instead, how does this idea grab folks: A hero only gains incremental XP when not in friendly territory (i.e outside his country borders) This would basically simulate the idea that the hero is off honing his hero skills in the wilderness. The hero would continue to gain experience as usual in his home country if his nation is at war...but when in extended peace, you'd have to put that hero at slight risk to get the promo point growth benefits.
I know this is unsolicited, and again, I should always caveat everything with the notion that this is the best mod I've ever seen in any gaming genere, but I dunno, I just think this sit and simmer possibility is just a bit strange.
-Steamer
PS: By the way, I 100% for this concept with Adepts, Mages, etc...since it would be relatively realistic for them to sequester themselves in a tower for years and years practicing igniting furniture and such. But whoever heard of a sword/bow wielding type sitting at the archery range or sparring with a haystuffed dummy for years to become legendary?