I've been thinking way too much on how this stat system is going to be played out. I like simplicity, but I also like effectiveness. I often find that smaller numbers yield much less flexibility, but they can be more visually comprehending.
I think what I will do is stick with a very simple design. There are five to six major stats a character needs to worry about:
LIFE AND AP
Life and AP are represented on the screen as orbs. It follows a similar style of Zelda, but more notably "The Illusion of Gaia" or "Actraiser II" (both made by Enix for SNES). Each stat point towards Life and AP will gain the character one orb, which contains 2 points. A character can increase these by exchanging Spheara to buy extra orbs. The max amount of Life and AP is 12 orbs, or 24 points.
These stats represent the attributes of the overall character. All abilities require one or more of these stats. One can improve their abilities by first improving these stats. Although higher-tier abilities can be obtained, they will still base off of the same stats. The maximum value of each stat will be about 20 (not sure yet).
There's actually a huge variety of classes that modify these stats. One begins as a Traveler. But, they have the option to begin training in one of these three classes:
A character also has a Class Rank. As this rank increases, they are given the opportunity to learn in the same class, or in another class. However, each level of the same class requires more Class Rank points in order to progress. The amount required is equal to the level they want to achieve. that means that a Level 3 Fighter must need 4 Rank points in order to become a Fighter of level 4.
The top level for each class is 10, which is Mastery. Furthermore, A character has 55 Class Ranks. To fully master one class, they must dedicate their entire Rank Points to it.
There is plenty of mixing and matching that can be done to get the character that fits right for you.