Missing scabbard part identification
 

Does anybody have a photo of what does the missing part of this scabbard look like? I am planning on having it remade.

It would be a section with a "hook" on it. It is Maguindanao and this type of scabbard has these on them.

José is probably fairly accurate to call it a "hook", but that work might give you the wrong impression. Basically what was in the insert area was another piece of wood with a slant cut at the bottom to help keep the sheath secured when stuck into a sash or waistband.
I took a couple of quick phone pics of my example. Mine covers the entire width of the sheath and was carved directly from the main piece of the sheath whereas the one on yours would be a separate piece and thinner, fitting into that insert space, either adhered with damar or wrapped with rattan or both.
Soory for the bad photos, but you should be able to get the idea from them. :)

David you are correct. I didn't know how to describe it. It is an added protrusion to hook onto a belt or sash.

Thank you for the insights!