Tim,
Very, very nice spear, thank you for sharing.
The decorative motif on the blade is the same as the one on a tebu sword we discussed a month ago:
http://vikingsword.com/vb/showthread.php?t=22101
At the base of your spear there are a couple of human faces if I am not mistaken, and those are very haram. Therefore I am with Colin in believing this to have been an animist, and not a Muslim object. It may have had ritual significance, or it may have been a status symbol based on the high level of workmanship (or both).
Regards,
Teodor