So we have strength, dexterity, vitality, intelligence, mind, and piety.

I think there should be encouragement for classes/jobs to pursue development in other areas.

Every 75 or 100 points of strength should increase inventory holding space by one, and improve chance of critical hit. Every 100 Dex points should increase evasion by .5% or some such thing, as well as increase accuracy. Every 50 vitality points should give a .5% chance you will have a critical guard, in which you take half damage or even 3/4ths damage. Every 100 intelligence points should give a 1% chance any technique or skill will deal strong elemental damage, essentially a magical critical hit regardless of class. Every 100 mind increases HP regeneration rate by 1%. Every 100 piety should reduce TP and MP costs by 1%. I think little things like that will make a huge but totally balanced difference, plus it'll encourage players to be different.