User blog comment:IamJakuhoRaikoben/Chapter 503: The Last Sight Seen, Review./@comment-84.197.239.101-20160926192137/@comment-84.197.239.101-20160928132705

Bloodman said he uses Curses, not that he doesn't have Magic. This means that he uses the Curses most of the time, but that he can still use some Magic should he need or want to.

Sure, he likely doesn't have as much magical power as most main chars and therefore wouldn't be able to spam spells, but he can cast one or several of them if required.

Other Etherious have been shown to use Magic as well, like Mard Geer's Telepathy and Kyouka's organic Link.

Still, there is simply no way you can argue that Ice Devil Slayer Magic is a Curse. It's Magic, always been and always will be.