User blog comment:IamJakuhoRaikoben/Chapter 518: Master Enchant, Review./@comment-7418318-20170121101147/@comment-5303512-20170122230632

Actually that brings another point that Brandish cannot change the size of anything beyond her power, this is clearly beyond her power, plus she is likely still in the underground room since Lucy is still there.

Erza destroying the meteor would make the most sense since that is what badasses do, they do the impossible.