Moose, you have a wonderful piece there (envy, envy, grumble, grumble....). I know that some engraving on blades are too shallow to have been inlaid. On your piece I am surprised to see inlay. This may raise a whole new set of questions for me and for the field if inlay were common in the engraving of these blades and just popped out. I do not think this is a maker's mark (especially since Filipinos/Moros/Indonesians did not use maker's marks) but perhaps a talismanic design. I think there could be a good argument for your whole blade once being inlaid seeing the pics you have posted. The material is a little harder to discern from the pics, it could be gold, brass, or tarnished silver (which can get a yellow-brownish oxidation depending upon the grade of silver and environmental chemical exposure). It looks to me that the whole channel was once inlaid and that most of it popped out.
By the way, etch the puppy and see what surprises are in store for you.
