Hi Bertie,
I wanted to send you a link to another thread that references copper blades on African knives -
here
Apparently copper blade have been used as a form of currency and/or as a sign of status and prestige. I've yet to get feedback if copper is also used on knives intended for tourists. However, I suspect copper may have more value than steel in such parts if the world, so I am mightily intrigued by the purpose of your knife and others like it.