Arek the Absolute

Hey man on MK, just go to the main options screen where you can see stuff such as your stats and stuff (Press triangle button) and you'll see "Grow Book" as a selectable option. Go there and you'll see how you can improve your stats; which is based on what items you've synthesized.

Also take note aside from the workshop there's that room (athanor room if I recall correctly) near the workshop where you can develope weapons/armor and accessories; they too are important to the stats of the characters. Once you've made them just look at the grow book and a slot to where you can improve your stats will light up. Allot the needed AP to "plug" in the stats.

Hope that explains things easily enough for ya. If you have any more questions or are having trouble understanding something don't hesitate to ask.