As a surname, Novian seems to be very rare. But it does seem to be
German, and originally to be that of a family from Mainz in Germany, as shown by the following website:
http://freepages.genealogy.rootsweb.ancestry.com/~frantzen/novian.html
I tend to think that the writers of "A Different World" created the name Novian for the character on their own, and that its resemblance to this rare
German family name is pure coincidence.