You know what would be fun? Have someone let the PCs know in advance that Strahd is going to try to steal their stuff. There's three ways that can go:
(1) PCs fail to thwart the theft and get crushed in their next confrontation with Strahd (unless they find a way to generate some other advantage).
(2) PCs thwart the theft, Strahd either tries again or just brings enough firepower to the party to win anyway.
(3) PCs manage to trick Strahd into thinking the theft has succeeded (Nystul's Magic Aura?), Strahd attacks them at his leisure, PCs go "Aha!" and whip out the sunsword/etc. anyway to his surprise and dismay, and then the PCs crush Strahd.
I'm looking forward to the look of horror on the party's face when the swarm of bats suddenly bands together and starts gnawing at their hands to disarm them of the sunsword, but these critters are weak enough that I don't think they'll have a HUGE chance to do it (swarms do not have great acrobatics/athletics scores, y'know?).
...and once the party knows that Strahd's first goal is to get rid of those items, it should be interesting.
Strahd charms a character and asks them to hand it over? Strahd uses the Shove action to knock a character away and into acid/spikes/whatever? Strahd focuses fire on a character with the items? Using decoys is certainly possible...for both groups.
I think it adds an interesting bit of game-within-a-game to the proceedings, and hopefully invokes that fear of loss in the party without necessarily going in for the kill. "We spent all this time, and all this effort, to get our hands on the
Holy Symbol of Ravenkind, and now the paladin who is wielding it was
charmed by Strahd, and then just gave it to him...." should result in a party that feels like they're fighting a clever, cautious, and absolutely nefarious adversary who is interested in
winning, and who, if they fight on his terms, will probably win.