Ideas are great to be shared, and I don't mean this in a horrible way, but blue mages going out and "wresting their strengths from their enemies" has always kind of been a staple of them throughout every final fantasy. Even in IX. I can't really see how a "school" where a blue mage learns their abilities to fit in well with the blue mage storyline either to be honest.

It sounds a little harsh, but I don't mean it to be this way. I respect blue mages for the spells they've managed to get (especially pre cap with sea spells); to me the suggestion is akin to suggesting a walk-in-wardrobe where you can copy and clone the equipment of anyone that walks in.