@Zaacna I don't know exactly but there was this small part somewhere which explained that Aria'sngrowth was faster than in her previous live and that it might have something to do with the use of the hourglass. This was speculating from Aria's point of view since she noticed the difference in growth so it might not be the actual reason for the difference.
Something like every time she uses it she becomes older because: A she pays the hourglass with part of her life or B everyones time gets reset exept hers so every time she uses it she becomes her age + the time the hourglass resets (altough I dont know if that accumalates to enough time to make her this mature looking) but if she uses it enough it could add months or years to her orignal age.
I don't really know if this makes sense but i did my best to explain so i hope this helps
Something like every time she uses it she becomes older because: A she pays the hourglass with part of her life or B everyones time gets reset exept hers so every time she uses it she becomes her age + the time the hourglass resets (altough I dont know if that accumalates to enough time to make her this mature looking) but if she uses it enough it could add months or years to her orignal age.
I don't really know if this makes sense but i did my best to explain so i hope this helps