I'd rather keep The War Machine where it is and at its current strength, but move the hero promotion to and make Lucian their official hero. I'd also make all Dragons much stronger, and give the Doviello the thematically appropriate "Challenge" spell (letting their melee units fight each other for xp).
I have mixed feelings about Lucian being a real hero.
True, he becomes obsolete after awhile, but he's already a BIG advantage in the early game, an axeman when everyone else the Doviello run into is a warrior.
He's a big key to a lot of my early game rushes with the Doviello to take out my unfortunate neighbors. He can usually soften up any especially tough units enough for a cadre of Beastmen to take enemy capitols.
If he was a real hero, he'd be even more powerful.
Actually, what I'd like most is for him to be upgrade-able I think.
Since I fight so much with him early, and since he has an early edge as an axeman, he usually doesn't have a hard time getting promotions. If I could bump him up to Champion-level or Paladin-level strength, then he'd be a force through the whole game.
As it is, I usually give him the Defensive promotion during my early conquests, which makes him an ok defensive unit for a long time.