User blog comment:Miskos3/Fairy Tail Chapter 488: The Two of Us, Always, Review/@comment-7418318-20160606133552/@comment-7418318-20160606164303

Not critical enough apparently. If he had made her go for a vital organ, she wouldn't even have needed to enlarge the blade.

That he controlls memories rather than actions doesn't seem like a good argument to me. No matter the finer details of how he did it, he was able to effectively plant the thought "I have to kill him" in her mind (or rather "He is the person I have to kill". If he instead had planted "I have to stab him through the heart" or "I have to kill him and make sure he's really dead" the chances of August dying for good would have been greatly increased I think.