I think a patina that is developed as a result of the use of the knife shows that it has been a tool, a collectors item. While I try to keep my knives clean, shiny is not a goal.
I have sometimes joked with friends who have worked in the Pacific Islands (as I have) that it is easy to recognize a knife, usually a machete, that was used by villagers in Samoa, Tonga, Chuuk, Papua New Guinea and similar places.
There is a distinctive, flat black patina produced by breadfruit sap, salt water and pig blood that instantly brands the tool as a genuine Pacific Islands Knife (PIK). The PIK will also have lost its wooden handle and has strips of bicycle inner tube wrapped around it as a substitute. While razor sharp from constant honing, an authentic PIK will also have numerous small nicks on the edge due to contact with volcanic rocks in the food garden. A genuine PIK has an honest patina that was earned, never forced.

Faiaoga