Some CON Questions

[Estellios]

All of Stanislaw's info is good, and I agree about prioritizing HP over MP. However I wanted to note that it has been pretty much confirmed that Water Potency does nothing for Cures.

Concerning Magic Accuracy Vs. Enfeebling Magic Potency, it seems best to think about it this way:

Magic Accuracy: The chance of a spell's primary effect being successful.
Enfeebling Potency: The success rate and potency of skills' added effects.

Magic Accuracy will boost your success rate with Repose/Sleep and its duration, as Sleep is its only effect. Enfeebling potency is used for skills like Shadowbind and spells like Aero. Aero's damage is its primary effect with the Bleed damage being a secondary effect. The Aero damage is affected by magic accuracy and is required to land unresisted to start a combo. The extra Bleed effect lands more reliably with higher Enfeebling magic and has a separate chance to land regardless of whether or not Aero itself is resisted, and since it's secondary the Bleed effect doesn't have to land in order for the Aero combo to start.