Weakness malus on nomad succession?

My question is the same as the title. Sometimes when I get a new ruler as a nomad I receive a malus called "Weakness" which decreases the clan sentiment of all clans. I'm not sure what triggers it, and it also varies in severity. Right now I have a new ruler with a malus of ~300, and I'm not sure how to get rid of it (and I don't want to fight all of my vassal clans at once). Does anybody know where it comes from and how to get rid of it? As far as I can tell, it is probably age-based, although prestige might play a factor.