Remember some weeks ago my question about a Philippino spear. Well, I finally bought it (and got a nice deal, too.

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I don't know much about it, but I guess it's Philippino. I would appreciate any comments of more knowledgeable forumites.
Total length is 161 cm. The spear blade measures 27,5 cm. The wooden shaft is thicker at the place where the spear blade enters the wood. At that spot there's also a metal ferule. No other decoration on the shaft. It has a metal spike at the bottom end of the shaft (length : 10 cm). The whole piece is very heavy. It reminds me of a harpoon. Is this a fighting spear ? What tribe ?
Look at the pics :