User blog comment:Miskos3/Fairy Tail 522 & 523: Gray's Trump Card & Is Destiny Burning, Review/@comment-112.134.46.61-20170218161514/@comment-112.134.45.19-20170219105838

Really, was there no other time during the entire run of the Fairy Tail story that Cana could have shown her powers, she has to get involved in a Gildarts fight of all people.

Mashima definitely has the right use his characters as he sees fit, they belong to him after all, however, weather or not the way he uses them in the story actually makes the story better or worse is up for debate. It would have worked with almost any other character, not Gildarts, its suspect story telling here. When you set out a character like Gildarts has been set out, as the cream of the crop, as the standard to which everyone in FT strives to achieve, this kind of thing just brings the character down a peg. He faced Acnologia alone and survived to tell the tale, and like Shanks from OP before him, loosing limbs and organs hasn't slowed him down. There are plenty of other places Cana can be more useful.