You put a well geared Monk there with Revenant Fists +2 or Verethragna and I can almost guarantee that they'll pull off a similar feat. The only reason he was keeping up with TP that quickly was because he had Retaliation up (at least, I believe he had Retaliation up), so that only would have worked if the mob was attacking him anyway. Every job that has a strong critical hit weaponskill (I say strong because there are weak early ones like Power Slash, Vorpal Scythe, etc) is going to do extremely well in Abyssea if they have Atma of the Razed Ruin.