yeah, something like that would be great. i have similar idea that i just posted (with some other ideas) few minutes ago. i will copy this specific suggestion here tho:
When you become powerful and blob away, there can always be a endless series of small useless wars. Everything from some random uprisings to the some count or duke revolting which becomes very tedious and
unimportant for the head of your awesome faimily and kingdom/empire to deal with. So i propose you could as a liege nominate (under high enough crown autority) one of your vassal to deal with this war in your name. (This could have evan be done in a way that this vassal becomes warleader and yourself gets a status of ally or even complety removed and get hostile status.) What that means is: Vassel you desigante would be honoured for your trust (imporved relations boost) and they would get the majority of prestige and war reparations/loot/ransoms (if won ofc). (Crown could take 10%). While i as a liege woundt need to micromanage small wars, save my manpower/income and i could evan still use diplomatic actions/decisions and evants that gets disabled during wars. But if vassal loses this war the liege would get 200% penalties like prestige lose, relatins penalty etc. Ofc as a liege you could intervene in the war if you see the vassal is losing and this could bring some other modifers with opinions and presitge, cassus bellies against imcompetent vassal etc.
