I just would like to add, that in this thread:
http://www.vikingsword.com/vb/showthread.php?t=11889
I described the same spear as from Adamawa (because the seller told me so that time). After then I saw several others, some of them in Kano, and the prevalent opinion of local people was Katsina, Sokoto. Nevertheless, the most important for the assignation would be, I think, link to some old author...
BTW - I have never seen particularly this spear complete in Nigeria - always only very rusty spearheads. I think this complete type of spear, i.e. with the shaft, is rare already. (When the local "antique-vendors" travel to the bush to bring new items for their antique shops in Abuja or Lagos, and they find complete spear, they always break off the spearhead. The reason is they are afraid of the many army check points on the roads and it is possible to hide spearhead better than the whole spear)