Titles. Your realm is at the top, and everyone in it is a baronet rather than a knight, for instance.
It's an interesting idea. Weren't nearly all nobles of britain "barons", if they didn't have a more prestigious title?
Who would get this? The realm with the most glory, or the realm with the most, say, military glory?
As it could be an idea to split up the various glory points into categories, and have the realm who has the most military glory have one perk, the one with the most economic glory another, and so on. As long as the perks don't break the balance, so special titles for unlanded nobles is one interesting idea for that.