As I thought, dragon-exclusive magic was something like that.
"Sadina has used both types of magic. In which case, if the Firo Rials' divine protection is not received during Class Up, you'll be able to use it?" (Naofumi)
"Let's see--is it like that?" (Sadina)
"No, I think it'd be considerably difficult. That aquatic beastman is heresy." (Gaelion)
"Is that so?" (Naofumi)