Before I use do this trick where I will raise all my troops except me and my heir, because I don't want me or my heir to get wounded, maimed or god forbid killed. I then go on to conquer the world while me and my heir sit on their fat asses and partying it up in the palace.
But I've been think that in the medieval times the kings and dukes and even HREmperors will most likely lead armies themselves, due to the notion of fedualism, it is really expected that all military endeavors for a particular nation will be spearheaded by its ruler. (This may not be the case for ERE and the caliphates, but I believe the early Islamic Caliphates' rapid expansion was due to the early Caliphs all being exceptional commanders and generals, and the Caliphates' later downfall was their reliance on their slave armies (Mamluks, etc), and even the historically expansionist ERE emperors had to have been at least competent military planners and macro-strategists).
So I think to make it more fun and challenging (and also to make more use of of the tutored skillset) to have a participation of a ruler in the campaigning army vastly deterministic of an army's morale and effectiveness. So maybe something like if your ruler is not campaigning alongside with the army then there will be a massive morale tank or other combat or logistic malus. Also IF you do decide to campaign then your nobles at home will more likely plot against you or each other as was the historical case when kings go to war. Also I think there should be a regent when you go on campaign (maybe your wife or mother) and they may or may not conspire against you (also historical common), and ultimately this should serve as a trade-off of whether you should expand often or be a more peaceful ruler (serving as a balance for those who want to WC). This is classically the case of many Crusader kings (heyoo) such as Richard Lionheart of England and Louis VII of France who despite being excellent generals or pious crusaders were considered subpar rulers because they were away from their domain for a great deal of time.
Also I think the additional military modifiers (like aggressive leader, planner, flanker, etc) to a ruler and all army leader should play a greater role. Think about it, a army of 20000 with really bad commanders (think mastermind theologian or elusive shadow types) should have no chance against an army of 10000 leaded by a brilliant general type. I think there should be a mod or fix that lets you check up on enemy army leaders and make your decision to engage based on that.
I know I may be RPing a bit here but I really do think this adds to the depth of the game, since it limits non-stop expansion for players. any thoughts?