Mid 60 is fine if you have the right personae and you play intelligently. Don't just sit there and eat mind-charged attacks. Obviously you're going to die. Make use of buffs and debuffs. Put your party on Direct Commands and attack/defend/heal as necessary.
If you still get wiped out from that even through guard, then you need to level up. That boss is level 75. Mid 60 (assuming 64-67) is the low end of what's reasonable to beat him, provided you have decent personae on hand and they're all around the 65 mark as well.
As for the debuffs, google for personae that have Rakunda. Or you could level to 67 and fuse Trumpeter, then level that to 73 and use Debilitate.