Here is a quote from Antonio Pigafetta, the chronicler of Ferdinand Magellan.
Those people of Polaoan [Palawan] go naked as do the others: almost all of them cultivate their fields. They have blowpipes with thick wooden arrows more than one palmo long, with harpoon points, and others tipped with fishbones, and poisoned with an herb; while others are tipped with points of bamboo like harpoon and are poisoned. At the end of the arrow they attach a little piece of softwood, instead of feathers. At the end of their blowpipes they fasten a bit of iron like a spearhead; and when they have shot all their arrows they fight with that.
(Pigafetta’s Account 1521 Part 2, 1898, The Shaping of Philippine History Vol. 2 no. 17, October 1998).
The dual purpose, blow pipe-spear is also found, so I have been told by Filipinos, in northern Luzon among the Igorot groups.
Ian.