Investment in a specific skill should also increase skill slots, instead of the Memory, which can still serve as a maximum skill slot limiter, like Con limits maximum APs.
Intelligence should additionally slowly reduce penalties for using higher level items or spells.
Therefore intelligent builds would be able to learn skills and spells more quickly and you can combine that with any build in a meaningful and easily understandable way.
At least partwise that is, how it was in the first game. You needed a certain skill level to learn specific spells and a specific number of spells and an effectivity of a spell depended on your intelligence. Also it reduced cooldown and Constitution influence you maximum AP.
