This is from tribes in the east of the Congo, Lokele,Mbole, ect. I would just clean it with oil and some grit paper {carefully} if the rust is heavy and stubborn, using your finger tips just on the hard bits. Then just oil and steel wool from heavy to fine. If the blade looks a bit stark after that try shoe wax. As for age , wood does not last that long in the tropics so the handle could be a replacement, the blade could be much older.
This picture from "Der fer et de fierte" paints a thousand words about how isolated some Congo people were untill quite recent times. The truck and the gentlemen in thier Sunday best.
