Maybe something along the lines of a class that has more traits unlocked lower level with fewer abilities until they get their Job which unlocks Blue Magic.
Then get 3 ability spots at 30, 2 at 35, 2 at 40, a specific ability and 1 slot at 45, and the "XI like their 2 hour" (I played most when it was a 2h cd)
Then they can learn 1 ability per level but at 50 only can select 8 Blue Magic Spells. The Hunger's log idea sounds like a great idea to go along with this.