User blog comment:IamJakuhoRaikoben/Chapter 452: The Prelude to the Final Battle, Review./@comment-26822192-20150914170412/@comment-24053170-20150915003724

That may seem to be the case, but remember that August knows all types of magic, who is to say he doesn't have a way of sealing Zeref? Sure he might not be able to kill him, but he probably has some form of magic that can seal zeref away if he wants.