don't rulers, if present, by definition lead the army whilst on the field? if they don't, they simply shouldn't be there?
i would suggest rulers and generals simply just get included in all army channels. (though that doesn't bode well for a rebel army in planning..... tricky to resolve?) seeing as that would be the main thing about armies, knowing where to go.
just add some bonus on top if present
Marshal X takes command of his army A
General Y oversees all armies of realm B
Ruler Y can be seen in the field of battle (or some such)
perhaps by default the general/ruler gets high cohesion?
