Hes like worse than omega weapon.
One easy strategy that worked for me:
Have 2 Dark Knights/Mascots equip the Valiant Lusture Garment Grid and Crystal Bangles. Have one equip an Oath Veil and the other equip Crystal Gloves, or just have both equip Crystal Gloves.
The other girl should be a gunner with the Highroad Winds garment grid equipped. Cat Nip and Speed Bracer should be the accessories.
The only girl who should do the attacking is your gunner. The other two Dark Knights should be healing with X-Potions and reviving the Gunner when necessary.
When you fight Paragon, either have your gunner attack herself in order to get herself into critical status, or just wait until she dies and revive her with a Phoenix down. One round of Trigger Happy should kill Paragon.
When you fight Trema, have your gunner use a soul spring to deplete all of Trema’s MP. No more Flares or Ultimas. Even if you do see "Ultima" or "Flare" appear, nothing will happen. Have your Dark Knights continue healing with X-Potions (remedies if Trema inflicts stop) and reviving your gunner. They should easily survive every single Meteor. 4-5 rounds of Trigger Happy should do it.
There are other strategies, but this one always worked for me.