Thank you anyway, Steve T ...I, too, had hoped for some useful leads. I'll check the Mabinogion (my supervisor, Sioned Davies, has published the most recent translation so she's something of an expert on it) for wands in general and also consult Dr Juliette Wood who is part of the same department and knows a lot about all manner of folklore.
One of the difficulties on this thread is the ability people have to try to see layers of meaning ...I'm baffled about how a question about Kay holding a wand as symbol of his authority can become a deep question of the source for deities, for example. This isn't meant to be an ungrateful dig or disrespectful comment, but it's generally best, in my experience, to first look at the obvious meaning of a question or a sentence.
Thanks to all who have tried. If I find out anything notable I'll be sure to let you all know!