"Er..." Signum has gone from confused to totally nonplussed.

"You didn't know about..." she begins, before stopping, taking a deep breath, and starting again. "Clearly this is an unusual situation. Let me begin at the beginning. Are you a mage, M--Hayate? Or at least, are you aware of the arcane arts?

If Hayate had enough mana to activate the Book of Darkness on accident, Signum certainly hopes she's a trained mage.