@Umesan almost all worlds of magic have a few standard rules regarding power and appearance:
#1 - a person's outward appearance does not always reflect their actual age or ability
#2 - as one's magical talent goes up, usually so do does their lifespan, and their rate of aging decreases proportionally
#3 - even if one actually is young, as long as they possess sufficient power and talent(s) they can hold a great deal of authority
#4 - the worse a noble's power base is, the more likely they are to be a power abusing dumb**** that will probably lose everything crossing the MC
#5 - never piss off the quiet ones, especially if it's a pretty boy or a goth loli girl hiding behind a couple buff fighters