first off improve the AI of the spirits so for instance when u have 9 hp the spirit doesnt cast haste or regan 1 instead of a cure 5 or curaga 4. another would be increase their stats so they have some real power to their spells similar to mob elementals of corresponding level and give them the dmg resistance similar to elementals. Something else would be to give them their own form of favor and maybe some form of basic command system for what kinda spell they cast.

Smn also really needs a stay command for when useing favor the avatar doesnt need to be attacking and feeding tp nor the smn standing in dmg range (they're really squishy).