Haridama Taima Juku

Kokuyo and Harika are a little unusual-
and not just because they're sorcery students. They're Obsidians, wizards who must use enchanted swords to help them cast spells. Their fellow students think Obsidians are inferior to "normal" wizards.
But Kokuyo and Harika have something that their cohorts don't:
the power of friendship!

(Source: Del Rey Manga)