Hi kalden yungdrung,
Yes I know as on Sunday I downloaded MacKenzie's concise and had a good look through but I didn't want to put anyone off as it is only a concise dictionary and might not have all the words. But I pretty much decided that it wasn't Pahlavi. This leaves two other options. Pahlavi was the late Persian language and there were a few others but the other main two are Avestan (language of Avesta) which is a sister language to Sanskrit and close and the other Old Persian. So I downloaded another Avestan glossary (44 pages). In the glossary I looked for words like wisdom & knowledge & know and the words are similar to Sanskrit (Vidya), vaedu, vidu and I even saw a word close to prajna. There is also an Avestan Dictionary book scan online (http://www.avesta.org/kanga/
) but as we can't read Avestan script it is not of use. There are many Indian and Persian Zoroastrians who can read it though.
Avestan glossary (I can't remember the link but can upload it somewhere if anyone wants it):
vaed-, pres. intens. voiuuid-, pres. caus. vaedaiia-, aor.
vaed-/°uuoid-, perf. vaed-, perf. part. viduuah-
(q.v.): to know.
prajñatár- “who knows the way.”
also other online smaller glossaries mentioned vaedu, vidu, etc.
The last option, and probably the solution, is that rig is originally from Old Persian. If it is then only a few professors can read that and you need to email them in their universities and simply ask if the word rig has meanings in Old Persian relationg to: knowledge/know/knowing, wisdom, gnosis or similar cases? Most of them should know a few other dead languages to some extent and it would be good to ask if rig occurs in any of them as far as they know. I think rig might rarely have been used in Aavestan or even Pahlavi but I now suspect it is from Old Persian.
On sunday I tried to search for the article on Bon that mentioned this etymology of rig. I know it was a pdf but after an hour I gave up. I know it wasn't by Dan or any of the other usual writers. I am sure if you post a topic on a Bon forum regarding Persian root of rig, someone will eventually step up or know the reference.
Finally on Sunday I was thinking about Avesta's counterpart in Hinduism which is the famous Rig-Veda. The Veda part is basically vidya/rigpa and the rig part as I said originally in this thread is usually translated by Sanskrit translators as praise or verse(s)/phrase(s). However I thought that rig originally could also have meant veda (vidya) too. And this double or triple barelling could mean both in praise of veda and phrases on veda (as is currently believed) but a third connotation could be using the same concept by two similar words about it to reinforce it. If I am right then rig could have also meant veda (vidya) in Sanskrit back in the mists of time. But later it's two other main uses took over. For that an expert on history of Sanskrit is needed probably, or maybe not, which is again only a few people. This is just my new pet theory. Good luck.