I finally have been reunited with my copy of Pokorny's IEW and
was able to clarify some info on the root Dan-.
I also realized, after consulting Lambert's La Langue
Gauloise, that the etymology of Gaulish Dan- as "violent" is may not be
completely precise, though not altogether off the mark (I misread the
etymology from an entry in the Endlicher glossary - a medieval glossing, in
Latin, of 17 Gaulish words - where Rodanus was glossed as "violent judge" in it,
with Ro- [leg. Hro-] given as "violent" and dan- given as "judge(ment)." Lambert
considers this a folk etymology and says we should ignore it - Lambert considers the dan- element in both Rodanus and Danuuio to be the
parent of Irish Danae "audacious/violent/hardy," so it is likely that the
author of the Endlicher glossary was right in the sense of "violent," but
misapplied the meaning to the element Ro- [PIE *pro], thus the confusion
of his etymology).
Pokorny gives the following:
DA- "liquid/flow," DANU- (fem.) "River"
Old Indic da-na, da-nu, Danu "water-demoness"
Avestan da-nu "river/storm," Danavo
"river-dweller"
Osset don "water/river"
Scythian Tanais (and Dniepr<Danu apara,
Dniester<Danu-nazdya)
Greek Danaoi, demos "animal fat"
Armenian ta-muk "wet"
Albanian dhjame "tallow/fat"
Gaulish Danuuio, Condate (*Kom-da-t-) "confluens"
Welsh Don, Irish Donend
Hittite dame(n)k "as rain falls"
-C Gwinn.