Introduction

The hinālung is a double-edged dagger or sometimes as large as a shortsword. They typically have a tang that is rolled into a socket of oval cross-section.¹

A Batad Ifugao dictionary says the following:

Noun
"A double-bladed bolo of various lengths, usually carried for self defense; large varieties are sometimes used for cutting trees."

Cultural note
"A double-bladed bolo is in one metal piece with a rolled handle, hālung, usually covered with a woven rattan handle covering, allūbung. One variety has a rolled handle base into which a wooden shaft may be inserted to be used, especially in the forest, as a spear." ²

I am personally skeptical about their use as a spearhead, for the following reasons:
1. Such use has never been documented, and seems to rely on guesswork by non-native observers.
2. Ifugao spears are typically tanged, not socketed.
3. Most men carried a spear or javelin anyway. Why would one need a knife that could be made into one? Especially since it's about as much effort to carry a spare headless shaft as it would be just to carry a complete spear.

Notes
1. Some more examples can be seen at vikingsword.com. 
2. Sil Philippines Languages entry hinālung.

This example

Somewhat larger than the reference examples I could find, more of a shortsword than a dagger. Blade is double-edged and leaf shaped, with diagonal tool marks. Edges are smoother, suggesting harder steel there, so I think it's a three-plate construction with a high carbon edge plate between two layers of softer iron or steel.

In handling it really feels like a good shortsword. Enough of a forward balance for heavy cuts. Very much like a good, stout Chinese jiàn.

Tang is hammered flat and rolled into a socket that serves as a hilt. It is wrapped with braided rattan for improved grip.

The scabbard consists of two pieces of wood, held together by two pieces of braided rattan. A third was probably once present at the top, now missing. The scabbard retains a rattan and plant fiber carrying strap.

Condition

Good, original, untouched condition. Some staining on blade, but stable. A split in the lower part of the scabbard and missing its rattan binding at the top.