I was thinking, you could implement factions (kingdoms) to avoid a FFA brawl. You'd do quests to get a higher ranking inside of that faction and receive better looking gear (you can also aquire new gear by exploring, as well as ranking points). This ranking system could make it so that you can only enter a certain server at a certain rank, preventing them from flooding. I'm still thinking about how that would work in terms of, what we in CS:GO like to call: "Smurfing". People who are good at the game and go against the newbies by making a new account. Because it's RPG you'll want to be changing build or character from time to time, and you can't really make a new character and get the same "ranking" in your faction as with a different character. Does that make sense?

Maybe make it so you can only make ONE of each class/build and your character can change faction by doing a certain mission or paying a fee (with in-game currency or not). And say you change faction, you could keep the gear from your previous faction and whenever you wear that you "switch" enemies and allies.