Make costumes wearable for all classes
Costumes should not be restricted by job class!
Since costumes don't have any stats and are style only they should be wearable by any job class. I know, that it would be very "nonofficialcustom" but we have custom hair styles, custom hair and cloth color and we even had different skin colors. Make any costume wearable by everyone seems just logical to me to have the top variety in character looks :)
The wiki page should be updated, no matter if you implement my suggestion or not, to answer that question: https://wiki.originsro.org/wiki/Costume_System