Currently waiting to even start investing materia into mine for 3 main reasons.

1. I already have my Yagrush, and while the stats fully upgraded for the relic would prove to be better, the amount of time & materia invested would personally not be worth it to me.

2. The added Mind and Spell Damage from the Turn 9 weapon is still superior to the amount of Determination you would gain from the relic, and for those of us raiding, it's only a matter of time, with no money spent (unless you count repair bills).

3. I worry for what they will do in the next installment of the Relic Quest. Will the stats reset entirely, and go back to whatever? Did all that materia grinding even do anything? I'm always skeptical of what square does for these quests because we have no idea what they plan to do, and judging from their sporadic change on this particular quest, I can only guess what the next quest will entail.

Although personally speaking I would go for Determination & Piety. Mostly because my current gear is factored around that very notion, and even if I added Crit, Spell Speed, or Accuracy to my relic, the amount I added would be so miniscule I wouldn't notice any difference.