[Galin]

My guess so far is that WAN- with this meaning (the bases GWAN- and GWAY- also appear in Words, Phrases And Passages, some entries having been deleted however) arose in 1959, 1960, around the same time as Quendi And Eldar.

Tolkien seems to ponder words for beautiful (WPP, base MIR-) while considering van and the fact that Arwen is dark-haired, and appears to answer himself with two bases in this context (here BAN- and GWAN-).

Also the editors for WPP often seem to note earlier or other appearances of a given base, sometimes pointing to QL or Etymologies, but for *WAN they merely note Q&E.

If Christopher Tolkien is correct that Dangweth Pengolodh might date to the early part of the 1950s rather than the later part, the form Banyai -- altered to Vanyar internally by the Elves themselves -- seems to suggest (keeping in mind I'm no linguist) a root BAN- and a possible meaning 'Beautiful Ones' at this point (although it might be added that this footnote does not apear in both versions, if I recall correctly).

Anyway I would be interested in Carl's response, and there could easily be other evidence I'm forgetting or don't have, even if my guess is well enough founded on this much.