Thanks, I was interested in this manga, but I've long since lost the patience to search for chapters in each and every group's site(that may or may not still be up) that decides to purge only the first chapters or the middle of the story.
If I had a nickel for every noble that pulled a surprise switcheroo at their engagement announcement in this chapter, I'd have two nickels. Which isn't a lot, but it's weird that it happened twice.
I have a feeling Robin's actual magic skill is deception. He's a con man, who can use his single magic skill to make others believe all sorts of things, including possessing multiple magic skills or being very talented. It's probably also good for simple nanpa, which allowed him to seduce the princess, as he apparently also sports a personality suitable for such practices.