How about a personal achievement diary that displays your 'achievements' with certain medals? Like you get a bronze skull medal for killing 10 players in pvp, silver for 100, gold for 1000.
And then different medals for different achievements like completing the jad minigame, capturing flags in castlewars, pest control games won, amount of bosses killed in godwars. You get different medals for them that can be viewed on your achievement diary, and you might also get different titles for it that are only displayed at the achievement diary, like 'Flag bearer Xxpur12' or 'Xxpur12, Terror of the Wilderness', etc etc. You can pick between your titles based on how many achievements you have
And there will be group achievements, like if you complete all achievements of a certain theme, like minigames, you get a big achievement for that. And ofcourse the 'Completionist' achievement when you have all the achievements.
I'm not sure if we can connect ingame benefits for it, probably will not be.
Ofcourse other players will be able to view your achievement diary (highscores/new button?)
Might draw out a concept for this.