User blog comment:MagnoCosmos/Celestial Spirits Ranking/@comment-5036235-20150908123253/@comment-7418318-20150908210139

To be fair, Torafusa didn't go into full-demon mode against Leo, but it's still quite the impressive feat, especially considering how Lucy was already weakened at the time and thus her Spirits should also have been below their best level, going by what Mard said to the Spirit King in the following episode.

I wouldn't put it past Leo to come out equal to (not Dragon Force) Gajeel if he and Lucy are at full power.