Honestly, this is more of a question than a answer, would Strahd taking a finger be an option? I started thinking of nonlethal solutions to this sort of problem beyond a slap on the wrist and although I think the other replies are a lot better, it would give Strahd a body part for the scrying spell.

The thing is I don’t exactly see Strahd having a hard time getting a lock of hair from a party member anyway, so it isn’t 100% needed and I can’t exactly imagine there being a graceful way of doing it (without heavily explaining it away with vampiric speed), which in front of Ireena, I feel like Strahd would try to be on his best behavior, and forcing somebody on the ground (dirty) to saw their finger off (messy) won’t leave a good impression.

But it could leave a lasting feeling for the pc if he figures out that he’ll be the target of the scrying spell for the rest of the game due to him disrespecting Strahd, or make it feel like utter bs (but then again, the alternative is still not pretty). I hope it never comes to this with my party, as I will have Strahd encounters, but I don’t want a pc to commit assisted suicide via Strahd.

Overall too psychotic for Strahd? (The ancient isn’t a brute after all)