My proposal:
Boat people. Specifically towboat people. Since the root only occurs in
http://en.wikipedia.org/wiki/Finno-Volgaic_languages (FW)
which grouping supposedly doesn't exist anymore, it might be a substrate loan in those FU languages.
*****GK: Apparently the first surviving notice of northern "Veneds" in classical sources is in Pliny. Strabo knows them not, nor does Pomponius Mela for whom beyond the Vistula there are "Sarmats" (III,28). So an interesting issue would be "what (who) was Pliny's source for his "Sarmati Venedi... usque ad Vistulam "(from Aeningia) (NH IV.97). Hypothesis: a Roman (or Germanic) amber trader, of the lot who jumped into the fray after Julianus reopened the route ca. 60 CE. There are interesting twists though. Pliny's source appears to be the same as Ptolemy's who speaks of the Sinus Venedicus with 'greater Venedic races' along it. And then plops in another source about the Gutones who wind up not on the seashore (as they in fact were) but "below" the Venedi...(a good example of "Ptolemaisms"). It's actually hard to judge if there really were a whole bunch of coastal Venedi there, or just one group whose name was applied to all, or if the name was
made up to explain the "Sinus Venedicus". What we can probably say is that the later "Vends" may somehow have been involved in the naming process. Some twenty years after Pliny, Tacitus has better information. Apparently it's not "Venedi" on the coast next to the Goths but... "Aestii" and a lot of them. But the name "Venedi" has acquired currency by then. So.. it's applied to some active "raider" groups in the interior, and henceforth sticks to them...It's not their self-appellation (but the Germanics pick it up). If such complications exist for making sense of 1rst c. CE data, should we even try to enter the darkness of thousands of years earlier? I'm not saying you're wrong. Good luck. I'll skip this one... And go back to trying to figure out how "Venedi' and "Lugiones" showed up in the eastern Alfold in 332, if I can find reasonable sources.*****