Returning to this topic from a "where do we go from here" standpoint. Providing a sense of alternate advancement. And providing the framework for a system so ZANY, it'll never get used (and also to incorporate RNG into it somehow).

Concept: All your excess EXP at Level 50 is stored up into a pool of... Excess EXP (we'll call it that and it in no way can be used to level you up once level cap is increased).

Excess EXP can be exchanged at guilds for unique materia of your choosing. But if we want to RNG it, the guild will hand you a random unique materia. If you get the same one twice, it goes the way of a primal weapon...

This unique materia provides traits that may reduce the cooldown of an ability (Swift War Drum, Swift Sacred Prism), reduce the TP cost of a weapon skill, reduce the MP cost of a magic spell, add an additional effect to an existing ability (i.e. Enhanced Cover, Enhanced Protect), or provide some other unique effect (successful parries increase TP, resisting a spell restores some MP, auto attack has a chance to afflict a debuff).

To make this materia more attractive, it would have a higher meld success rate than other materia. To make you cry, if you try to fit multiple unique materia on to have awesome traits, you could blow the item up just like any other materia. But don't worry, your excess XP wasn't getting used anyway, so it's like you didn't lose anything to begin with? Maybe...? Not really.

Rested bonus gets used up to accelerate the gain of this Excess XP.

But as this is not a guaranteed form of advancement, perhaps I will wait until 2.0 and put forth the suggestion of this...

tldr: Please add materia with traits.