Tiny silver antique knife

This is a very small knife, probably from Japan (my father was there during the occupation) or possibly China.  Inside the outer case is a brass sheath (not shown).  The outer case and handle are beautifully engraved with peonies.  The blade has a faint signature and is fairly sharp (unlike a letter opener).  I suspect it is some kind of a lady's knife, but don't know.  The bezel around the sheath has come loose, but could be refixed.  There is some corrosion where the blade meets the handle, and it needs a bit of polishing, but it's a beautiful little piece.  I'd love to know for sure what it is and what it's worth.

Fair