User blog comment:IamJakuhoRaikoben/Chapter 457: Naked Battle, Review./@comment-7418318-20151019081930/@comment-7418318-20151019133947

So far Ajeel defended against everything Erza was able to dish out without even breaking a sweat. She didn't do so much as put a scratch on him.

And now all of a sudden, she can slash him so badly that he practically fountains out blood from a wound that would be fatal to a normal Human.

If such a massive shift in the battle-tide came just from "being inspired" I would indeed call that illogical. Being inspired won't help a shooter's bullets to suddenly punch through a bullet-proof vest or sword-fighting knight to punch clean through an armour plate he failed to puncture with all his previous attacks.

But luckily here it can be explained away with Ajeel not paying attention and having to pay the price for it.