Might I suggest self-imposed "role-playing" to lighten the easiness? After all, no army would have been entirely composed of elite units. Consider limiting yourself to a certain percentage of "elites" in a given stack. Require all stacks to be led by a general at all times. Pretend your generals have their own goals, ambitions, and faults, and try to play them up. Is your general reckless? Launch ill-advised attacks against superior foes without stopping to retrain war-weary soldiers.
Cheers.