User blog comment:Wrath022/Chapter 517: Wendy Belserion, Review/@comment-5303512-20170115110137/@comment-7418318-20170115172046

Erza got beaten to a bloody pulp in the fight against Ajeel. While Wendy did some healing, she wasn't fully healed.

In that state she made the march to another frontline, where she got totally wrecked by Neinhart.

And now !!WITHOUT ANY FURTHER HEALING!! she fought against Irene, where she got pretty badly banged up again.

By all acounts Erza shouldn't merely be exhausted, but dead twice over. That's a hell of a lot of damage and exhaustion that Larcade's magic would have had to deal to Irene for her to lose even an equal amount of power to what Erza should have lost... and to bring her down to Erza's level... yeah, no way.