For what it's worth, Mikumo only seems momentarily bemused by that before returning to her usual demeanour. It's not the kind of thing she'd see in her world, admittedly, but she has seen abilities here that work somewhat similarly.

"So it's a magical item, then. Did you have to retrieve it from the Sylphid?"

It seems like an item brought from home, and Mikumo lost basically anything on her except her communication device, so she figures this would've fallen under useful enough to be confiscated if it can hammerspace store items.