This one you won't like:
An attempt on an etymology foe Ariovist:
PGmc. *xarja-gastiz ->
Suebian *xérj&Gest- ->
through an Gaulish-Latin interpreter (Ariovist spoke Gaulish, Caesar
spoke no Gaulish)
*arjo-wist- (interpreter identifies the unknown *xerj&- with Celtic
*arjo- "noble", replaces unknown (to him) -G- with -w-)
cf.
http://en.wikipedia.org/wiki/List_of_names_of_Odin
Sigh. I must be a masochist.
Torsten