Royal of [Realm] is a title given to all former rulers of a realm who ruled for a significant amount of time. It means you can't be banned by the judge and it's a higher ranking title than knight.
I'd be in favour of making it a realm government setting so realms can choose what the title says. For example, Royal of Highmarch doesn't make sense because it's a democracy, but Statesman of Highmarch would. Similarly, Prince of Luria Nova might make more sense than Royal of Luria Nova.
Poll