Group of African spears, Batonka? Zambesi River area?

[katana]

Purchased these spearheads a while ago, all 4 bought together from a militaria collector. These were part of a lot dated 18c-19c.
I have had difficulty in finding the origins of these spear heads, until I found this listing from Therion Arms.

http://cgi.ebay.co.uk/ws/eBayISAPI.d...MEWA%3AIT&rd=1

The spear heads are tanged and secured by iron banding, very, very similar to the spear listed above. Each of the spear heads have approximately 6-7'' of the original shaft attached. A real shame that someone decided to shorten them . One of the spears seems certainly, to be a fishing spear/harpoon. The large spearhead, is very heavy, the shaft is 1.5'' (3.75 cms) diameter and would surely be a stabbing spear. The other 2 (barbed) are not symmetrical, in that they look as if they have lost some of the barbs. But as far as I can tell they were manufactured that way. Any help/comments will be gratefully received, thankyou.