Just a suggestion, but I feel like it might be better to give players a certain number of stat points to distribute over the stats, to better establish what they specialize in, what they're average in, and what they don't even care about.

There are 7 different stats, and there are 7 ranks. Assuming that C is normal, set F as 0, E as 1, D as 2, and so on.

After that, give every player 21 points, meaning that they can become C rank for all stats across the board. Thus, there's a simple way of doing some degree of balance when it comes to stat distribution. Then, just come up with simple 1-point bonuses for selecting different classes.

While I'm at it...got a question. Intelligence determines the power of spells. Does that relate to skills (think about a Warrior's 'spells'), or no?