A number of sages populate the world, but are few and far between.
The only sage in Rosgoe, Elzgard sounds like John Houseman. He is a lifetime scholar of the Maran Cadax.
As a sage, Garvin is an old man. The password to his house in Shasta is “the wolf is fey”. He is a known expert on the Carmarthen Service. He also seems to know more about the stones.
Sedonius lives in Bamphf. He is the reigining expert on the stones.