User blog comment:IamJakuhoRaikoben/Chapter 492: Elder Sister and Younger Sister, Review./@comment-25111584-20160704162214/@comment-3290324-20160704163138

I disagree completely. Those two are the enchantments of one of the two strongest Spriggans. And while they are childish, being annoying and childish doesn't have anything to do with strength. And for that matter, this wasn't a full fight. Mirajane, for obvious reasons, was in a rush, so she jumped from base SS all the way to a powerful Take Over that severely drains her Magic Power to end the fight quickly.