Do you really want to upgrade a champion to 6* right now? I just ask because I don't see any useless 5 star lvl 1 champs that are not upgraded. Technically you could bring a champ to lvl 60 right now, but do you really want to sacrifice a upgraded lvl 50 Warmaiden to bring Elhain to 60 or the other way round?
You allready have a nice arena team for bronze tier: High Khatun, Spirithost, Warmaieden, Elhain (or Athel). Speed, Atk-Buff, Def-Debuff, Damage. Bring the damagedealer to 60 and it will work for a while. You need better champs later on, but that is allways a fact in this game until you find all the top tier epics and legendaries.