So, it's a bit of a stretch, perhaps, to tie this into Paganism, but I'm not going to rehash xenomancy or xylomancy, either.
In the craft, I see this as a guide who leads a seeker in some way. It could be one who guides you through a vision-quest, to the dreaming places, or in the practical ways of spells, etc...
We all need guidance or a tour-guide at some point in our spiritual walk. I believe (and have experienced) that these xenagogues arrive just when we need them or call to/for them.
I am grateful for all of those xenagogues who've helped me navigate uncharted (at least by me, anyway) territory.