WINID is the same as
WENDEL. The Wends maybe had their name from the
German verb "wenden" (turn) or "wandeln" (wander), related to "wandern" (the same). It's also related to the name of the Vandals.
This is partly taken from:
Ernst Förstemann: Altdeutsche Personennamen (1906)
Henning Kaufmann: Altdeutsche Personennamen, Ergänzungsband (1968)