African "throwing knives"

[Marcus]

There are many different styles of African “throwing knives”. I attach pictures of two, a so call Fang Bird’s head type, and a representative of the many different types associated with the various Kirdi (non-Muslim) tribes. These are often of complex irregular shape, perhaps with the idea that the more edges there are the better chance you will hit something if you do indeed throw it.
Can anyone speak on the issue of the ballistic character of such pieces of metal, or what their effectiveness would be when used in the dense forests of Africa? It seems likely to me that if some one threw them and missed, the intended target would just picked them up and throw them back. A pilum, the javelin of Roman legionnaires, had a wood shaft and then a relatively thin metal shank before the spearhead. The idea was that the shanks would be likely to bend if the spear hit ground rather than flesh and this would render the pilum ballistically compromised. Does the same idea hold for these items?
To what degree were these really used as weapons, or were they mainly ceremonial/symbolic? I know that they were also sometimes used as currency, although perhaps currency is too western a term. As I understand it, some of these items might be included in a bride price or tributary gift.

Comments?

Marcus