The whistle is pretty but entirely ordinary looking to V's eyes. He senses no demonic energy from it, nothing that might say aha! this, this is something extraordinary! Given the cavern they leave behind, that should not surprise him. This world is full of wonders. Plus— surviving a trial? They come with rewards? That is a curious bit of information.

"Have you a cord or thread?" V asks, "Perhaps we might string the whistles and lay it round both our necks to bind us both to its blow."

It may be tomfoolery, uselessness, something unnecessary to work or pointless to try, yet this place needs some kind of logic.