If I remember correctly in “Rise of Nations”, there was/is a category for a General and/or hero who could give extra “strength”, “hit points” to fighting units for a period of time. There is a precedent in the current AOE II DE, priests can heal units in their vicinity, so they can fight on a little longer. Could a such unit such as a General be added in some future update?
I would recommend that you could not access this unit until you were at the Imperial age with a university (add an Academy such as in Age of Empires). In addition the General/hero unit would need to recharge. Also the cost of the unit should be quite expensive. Just a thought, I think it would add a certain dimension to the game.