DAYAK SPEAR BLADES CAN BE QUITE LARGE AND ARE OFTEN ATTACHED TO THE SIDE OF THE SHAFT INSTEAD OF IN A HOLE IN THE END AS MOST SPEARS ARE.
SUMPTIN BLADES ARE SMALL AND LIGHT, THEY ARE ALSO ATTACHED TO THE SIDE SO AS NOT TO PLUG THE BLOWPIPE. THIS ITEM APPEARS TO BE A BIT OVER 12 INCHES LONG AND BEING BRASS OR BRONZE WILL BE QUITE HEAVY NOT LIKELY TO BE USED ON THE END OF A BLOWPIPE (TOO HEAVY).
I WOULD GUESS IT IS FOR CERMEONIAL OR TAILSMANIC USE PERHAPS A WEAPON FOR PROTECTION FROM EVIL SPIRITS. IT WAS LIKELY ATTACHED TO A SHAFT OF SOME SORT, IF A BLOWPIPE WAS USED PERHAPS IT WAS FOR SHOOTING EVIL SPIRITS SO MAGIC WAS MORE IMPORTANT THAN ACCURACY. JUST A FEW GUESSES UNFORTUNATELY NO DOCUMENTED FACTS. A VERY INTERESTING ITEM