[BahamutKaiser]

I think it will heavily depend on how well the add defensive counters and reeling attacks onto Gladiators skills. If the Assassin can do more damage in spurts, and outmaneuver him he's going to win, but if the Gladiator can counteract his spikes with counteractive attack skills, and stifle his maneuverability with stunning and knockdown attacks, it would be fairly balanced.