Reiji learned many things about the Arcana through Lord Castillo's explanation.
Although he is technically an Arcana as well, he doesn't have prior knowledge about them and he only accumulates information through his journey in this world.
Of course, he also learned a few things from the Guide that was together with him from the beginning.
He realized that it was fun learning about the potential of a summoned arcana.
That's right, he didn't think too much about their origin before, but now that he learned about them, he was somehow looking forward to meeting other Arcana like him.
Aside from that, he already had a guess that all the Arcana in this world is being handled by a specific Deity…
For example, all sword-related Arcana must be under Albeiron's jurisdiction… So there must be deities for the spear, rings, daggers, gauntlet, armors, and others…