Still need a clear pic of tang. The type and color of the rust is important
in dating the tanto even tho it is not signed.
The tsuba is not original to the piece as it is cut out for kozuka and kogai
but the saya has no slots for them. Not unusual. A lot of tsuba switching
went on even back in Edo times.
Rich
The Japanese Sword Index
http://www.geocities.com/alchemyst/nihonto.htm