Actually, this isn’t a bad idea. Just worded poorly. But to balance they should also give a drawback.
Winter t11 reskins could give +1 wis and -1 vit (little nippy)
winter t12 +1 spd -1 def (pretty cold so you slip on ice)
Valentines +5 hp -1 atk (you’re full of love)
Sun +1 dex -5 mp (full of stamina, but there is no school)
Oryx +1 def -5 hp (big old tank)