They decide on an unusually equitable engagement, while they're raising eyebrows anyways. Iomedae gives Alfirin an engagement rifle, which she wears slung across her back whenever she’s out of their quarters. Alfirin gives Iomedae the spellbooks with all her combat spells, (though not the one with alter self because she intends to keep making that point until they’re married) and she carries one around in a custom holster opposite her pistol.
It’s not a very elaborate wedding, for the richest people in the world. They keep it small enough that they can use Iomedae’s name in the ceremony without spilling any state secrets. That means they mostly only invite important Lastwallers, but they don’t actually have very many people they’d want to invite who aren’t important Lastwallers anyways. They invite Nefreti Clepati but she says it’s not worth her time to show up if nobody’s going to get to see it anyways.