As far as I know, the wrist knifes are more eastern Africa. rather than central Africa. I see them regularly with a tribal art dealer that visits kenya on yearly basis.
There are some nice pictures of a fight with these knives in Lenie Riefenstahl's book "AFRICA". The fight she pictured is an organised fight, like we would have boxing fights. On the web I found this picture.
I am sure more will follow from other forumites
Best regards,
Willem