Kai to answer your question, mine is probably Tausug. I suspect that Maurice's is also based on the curve of the upper tail part (what's left) and the curve of the beak. Yakans are completely different and Samal are shorter and more abrupt in the okir. The only other possibility might be Tawi-Tawi or even (though more remotely) Borneo Moros.
One other note, I don't think this is a fighter piece. Ususally fighter's are not as ornately decorated due to battle conditions but are plainer.
On my tagub, it was originally in pieces - I had to do a lot of restoration in putting all the pieces together and even carving new parts to match. Below is a picture of the scabbard before I repaired it:
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