Playing a loyal vassal is very thankless from your liege. Maybe have a counter (how many times has this vassal offered to join my wars? How many raids has he repelled?) Number reaches high enough, next available county is his, or one of his relatives.
#AI lieges should reward good vassals with more than opinion.
nova ore
narrow wing
I'd love if my liege hosted a feast in my honour after I help win a war, especially if this is mentioned within the event itself