as I play healer as main, I find a bit disadvantagment in the achievements:
100 pvp points + 100 pvp points at the fort/siege. You simply dont get any pvp points as bishop neither as supports like sws/bd. And these classes are imortant in the sieges, but they don't get better/farm like others DDs does by gathering achievements. If you want to stay it like this and keep it "harder" for support classes, then ok, but I though this information would help you. Thank for your time :)
firts, I thougt to add some achievemnts like Land debuff on enemy or Cancel debuff on ally or Heal ally, but then I think most effective should be just add Assist the kill, where assists are achieve only if you play support class.