User blog comment:IamJakuhoRaikoben/Chapter 386: Galaxia Blade, Review./@comment-4829046-20140602115018/@comment-7418318-20140602120111

That makes a lot of sense. So he might only be called a Demon Slayer because of the role he has within Tartaros rather than a unique curse.

But on the other hand there's this short conversation he had with the Lizardman messenger at the grave. There he said something about consuming devil souls. If that was literal rather than metaphorically (like the Mermaid devouring a Tiger comment by Kagura in the GMG), it could still be that he has unique abilities that make him better at fighting other Demons (something like Demons slayn by him being impossible to re-summon or being revived through Hell's Core).