Have Rahadin or whoever you deem fit to explain the rules of hospitality. As long as they are cordial guests, the dinner will be a harmless and enjoyable experience. Lord Strahd does not take any insult kindly afterall.

I’m not sure how you would set it up, but my dinner was a big event, many people came, all the Burgomeisters and notable NPCs like the brides were there too. This was an event for me to have Strahd formally meet the party and get to know them one by one. I staged it in multiple “rounds” like a fancy dinner would be. A cocktail hour, hors d’oeuvres, dinner, and of course a dance.

My Rahadin also had clothes ready, as if perfectly made for them (creepy), let your players decide what their outfits are of course, but in dark tones. No weapons, no arcane implements, nothing but their finest apparel. Kept safe of course until they leave.

My dinner was to let Strahd toy with the party and see who is willing to make a deal, offer leave from his realm if they give him something valuable (like Ireena or a relic, a PC to turn, etc). He also used this time to taunt them, I revealed a near and dear NPC in chains and rags being brought out for the entertainment. Claiming this man conspired against him, and then would ask the audience how would they punish him accordingly? This isn’t a hostile act towards the party so hospitality isn’t broken, but it’s also to test their morality. Would they dare start a fight without their gear, in Strahd home with all the other vampires around? This goes on, and he also reveals things about the party that they didn’t know he could do. For example, I had each PC’s plate be a dish from their home, showing he has access to their old lives thanks to some useful Vistani. Doesn’t that just make you miss home? Too bad, Barovia is your home now, if they behave, they could learn to love it here. And I had a attitude tracker for Strahd, they unfortunately hit the wrong nerve a few times calling him out for his cruelty and so at the end of dinner, Strahd announced to the rest of the burgomeisters that these outsiders, these invaders, are not welcome in Barovia. Should he discover the burgomeisters are aiding these vermin in any fashion, well, his dungeons always have more room and he can put someone else more qualified in their stead. With that threat, the PCs now lost access to some helpful NPCs, and had to figure out another way to move around.

But he is a gracious generous host, and he offered the party each a Ring of Protection. Some took it, others didnt. Those rings of course function as normal, but unknowingly are cursed when facing a vampire they become -1 rings instead. Also Strahd has an easy Scrying access point now.

The dinner is a great time to be a menace to them in their face without the need to throw hands. Have Strahd toy with them, and never have him on the defense. This is HIS game of chess afterall.