I can't actually find anything on Google about the etymology of these
suffixes. Would anyone here happen to have a suggestion on sources that
might?
In the meantime, I have drawn up some theories as to their origin with theoretical compounded roots, in an exercise of speculation. As mentioned above though, I am not aware of any etymologies given for these suffixes, so I am not aware of any extra-Germanic reflexes, which would definitely change things.
On the former, I've come across a root
*h₃eigʰ-, "to go away", as listed in LIV2, which could potentially give
Pre-Germanic *-h₃ingʰós, "from, coming from(?)" if it were derived from a nasal present infix form. The two nasal present reflexes of the root, Ancient Greek
oikhnéō, "to go, come" and Armenian
iǰanem "to come down, go down, descend", on the other hand, show a nasal suffix rather than infix, which kind of hampers this theory. (Although Beekes mentions they both may be innovations.)
On the latter, discounting the variant *
-ingō, which could possibly have arisen secondarily, I assume the Pre-Germanic form
*-Hn̥kéh₂ or
*-Hn̥gʰeh₂, But I can't really find a root with reasonable semantics. The best I could find is
*h₂neḱ-, "to reach, obtain", in which case the Pre-Germanic suffix could have been
*-h₂n̥ḱéh₂, "a reaching, accomplishing".
If *
-ingō isn't a secondary form, then the required root would have to be *h₁e(n)k- or
*h₁e(n)gʰ-. Yet I have not found a root of such form with a reasonable semantic basis.
If there are generally accepted etymologies for these two, I would really appreciate reading them.
Thank you for your time.