User blog comment:IamJakuhoRaikoben/Chapter 495: I'm Hungry As Hell, Review./@comment-141.0.14.146-20160725164520/@comment-3045936-20160725211232

That would assume that Gildarts could break August's Magic. Yes Gildart has always been strong. But during the GMG, Jura the 5th Ranked Saint, was considered strong enough to challenge Gildarts by Markarov. So after a year I could see him raising to a Spriggan Level Mage. But August is still the strongest Spriggan and considered the strongest Mage by Mavis.

I think it also explains why Irene can be consider his just shy of an equal. Irene's Magic Power is just a bit lesser than August, like so little it doesn't matter. It's the types of Magic they use. August is rumored to know countless types of the past and present, while Irene seems to know magic of the new era, Universe One. That is why I think, August thought even he couldn't defeat Achologia, as Achologia would have seen all of his Magic as they are of the past and current eras. While Irene's wasn't. So August is strong for knowing the past and present of magic, and Irene for knowing the future development of Magic.

So I don't think Gildarts could have down overall much, unless he grew past the standard Spriggan Level. I can see him defeating Historia God Serena, now but maybe not back during the Tenro Arc.