Try

Leonel didn't seem to hear Aliard's cry of pain. He had already closed in the distance to Margrave.

"[Darkness Do--]!"

"[Light Domain]."

Leonel's indifferent voice cut through it all.

The original creator of [Light Domain] didn't spend years of research constructing this spell so that it could enhance Light Elemental Arts. Though it worked out this way, it could only be considered a mere afterthought, an unexpected position outcome.

The main reason it was created wasn't to boost the light, but to restrain the dark!

Leonel could tell that the reason Margrave was so good with the Dark Element was because it wasn't a simple affinity. Leonel was certain that manipulation of darkness was Margrave's ability, not much unlike the little mink.