Real or fake, it was an enlightening encounter. I wonder if the original ended up in my version of Hell or if he was simply voided upon his reliquary's destruction. [He clicks his tongue.] Sloppy work, that, binding his soul to a physical object. Particularly one so fragile.

[He hums thoughtfully to himself as his form returns to normal.]

Judging from the look of it, the reliquary itself was the source of his magic, not his own being. A battery for magical energy of sorts. A quick and dirty way to obtain power but ultimately limited as you saw: just raw energy with nothing to direct it.

Though given how sloppily-done it was, perhaps the binding wasn't intentional. Magic is energy. [He spreads his hands, red-colored light flowing off of the tips of the claws of his left hand and going to his right.] All energy has a tendency to flow along the path of least resistance. In magic's case, unless you're very careful when casting, it will answer the letter of the words used in the spell rather than the intention. He might have attempted to cast something but poorly-worded the spell.

Or he was utterly incompetent. Even odds, I'd say.