I was informed in the other settlement that it is used for rituals, usually with animal sacrifice, and that it's supposed to be highly regulated.

[Alucard doesn't let go of the sample. It is the only one he has now, the rest of the pile burnt and then burnt again to be on the safe side.]

It's supposed to be blessed by elders too. Multiple times. Which is also worrying. But that was it. I've half a mind to contact Luna and ask for their perspective.