CONGRADULATIONS ON A VERY INTERESTING AND RARE ITEM.
I WOULD CLASSIFY IT AS A PRESTIGE, CEREMONIAL OR SYMBOL OF RANK ITEM FIRST AND A SPEAR SECONDARY. THE CARVED HEADS REMIND ME OF BATAK DECORATION, THERE IS DAYAK DESIGN ALSO AND THE FANCY CHIP CARVING AND COLUMN STYLE CARVING I CAN'T PLACE
THE FINAL REMINDS ME OF A LOTUS BUD FORM SEEN IN INDIA, CHINA ECT. ,SO IT STRIKES ME AS A VARIETY OF CARVING FORMS. THE SPEAR POINT IS A VERY UNUSUAL FORM ALSO AND APPEARS TO BE OF VERY HIGH QUALITY, IT MAY BE EASIER TO PIN DOWN AS TO ORIGIN THAN THE CARVEING STYLES.
I HOPE YOU CAN GET SOME GOOD INFORMATION FROM THE MUSEUM ON THIS MOST INTERESTING ITEM. GOOD LUCK