I personally went primary PARRY, secondary ACC. PARRY is your only tanking stat, so even is its not great, its still a little more mitigation.

Besides If you wanted to do more DPS, its much more effective to use crafted DPS accessories with Vitality melded, If you don't want to spend to much, try using a ACC Materia IV on the 100% slot, and 4 Vit III on the remaining ones to cap VIT, should be fairly cheap and you get much more from that that a few DET points on the weapon really.