User blog comment:Wrath022/Chapter 516: The Truth About Enchantment, Review/@comment-2214433-20161226235007/@comment-5303512-20161227051017

Do you mean by time or restrictions? Because there is a difference between both.

Irene was IC so of course she is going to underestimate her opponents, Shounen enemies do that a lot.

And the fact that Irene's head was not split open means she must have enchanted herself to be stronger than how much force Erza swing with.