Hello Lew,
I am not saying that this dagger is not from the Philippines and I agree with you that the scabbard looks more Philippine than Mexican in its overall style and construction. While the overall appearance of this dagger gives me the same impression of being of Philippine origin I would have expected it to have a raised medial ridge on at least one side of the blade but at the same time I have a small dagger from the Visayans with a very similar blade profile that also does not have a pronounced medial ridge. Like I stated earlier the stacked dark horn and bone (or is it blond horn) hilt is what I have not seen on a Philippine piece before. I am sure that the Mexican people who were brought to the Philippines in the early 1800's or even later had the same opportunity to influence the style of some of the weapons produced there as did the Chinese, Spanish and Americans (look at all the Bowie knives). As for age I would guess this to be from 1900-1930's and I would still like to have it in my collection.
Robert