"to rub or scour to brightness;" figuratively, "to clear from taint or stain, renew the glory or brightness of; renovate," late 14c. (implied mid-13c. in the surname Furbisher), from Old French forbiss-, present-participle stem of forbir "to polish, burnish; mend, repair" (12c., Modern French fourbir). This is from a Germanic source, from Proto-Germanic *furbjan "cause to have a (good) appearance" (compare Old High German furban "to polish"), from PIE *prep- "to appear," which is perhaps identical with *kwrep- "body, appearance" (see corporeal). Related: Furbished; furbishing.
The Old English cognate of the Germanic verbs, feormian (with unetymological -m-) meant "to clean, to rub bright, to polish." The surname Frobisher is a metathesized form of the agent noun. "This was a business of considerable importance when armour and arms were in general use, and were in continual need of furbishing, or scrubbing" [Wright, "Anglo-Saxon and Old English Vocabularies"].