Is there any reason these are two separate tags? My original guess was one referred directly to the RO class while the other was ambiguous, but if you actually go through the tags over 90% of both of them refer to the RO class anyway.
The only problem I see is that there are a few images such as post #388008 that seem to be using it as just a vague term. If it gets aliased though, I'd be willing to go through it and try to sort those ones out. There's also a lot of RO ones that should be changed to the high_priest tag anyway, so it'd be like killing two birds with one stone.
EDIT: On second thought, if there was a way to search for the priest/priestess tag while omitting images if they also contained the ragnarok_online tag, that would probably make the whole process of filtering out the non-RO ones even easier.
Thoughts?
Updated