User blog comment:IamJakuhoRaikoben/Chapter 452: The Prelude to the Final Battle, Review./@comment-26884814-20150914210434/@comment-7418318-20150918231809

Actually I meant the dust thing literal.

Sure his unintentional death-wave "only" kills while leaving the body more or less intact, as could be seen with Zancrow, but remember the plants that withered, died and turned to dust just because they were close to him or those errosion balls he shot at Ultear, that vaporized solid rock.

I'm sure if Zeref put some effort into it, he could do the same things to a Human body too. And that's just with the magic we've seen him use already. Who knows what kind of other spells this genius wizard still has up his sleeves that we know nothing about yet.