I think Ragnarok Online is simply too inconsistent in artists depictions. With over 25,000 images on gelbooru alone I thought it would be easy but at best I get depictions of the wrong class mixed in with, I dunno what. I ask for an acolyte (ragnarok online) I get ... indescribable, I ask for priest I get boys, I ask for priestess I get some character from an anime or something? I ask for archer (ragnarok online) I get Archer from Fate, I ask for mage (ragnarok online) I get some non descript character. With all the images on boorus I thought Ragnarok Online would be easy but I guess there's too much variation as everyone has their own character they're drawing as a "priestess" or "mage" or whatever and there's too much crossover with other anime and games about what a "priest" is.

Ahh well. I think this is about the closest I got. Not what I asked for but after dozens of images I'll take what I can get; a high priestess walking down the road.