The European font Roman numerals on both sword and scabbard is what makes me lean toward European origin. French, Prussian, Austrian all had matching serial numbers on swords/bayonets and scabbards. Supply system micromanagement. Some US weapons, some British, some Dutch, some Japanese. And others.
It doesn't look like anything I've ever seen come out of the Philippines or any east Asia country for that matter.
Highly possible that it was taken by a Japanese soldier from an armory on one of the Dutch East Indies islands, from Hong Kong, Singapore, Malaysia, etc and then the Japanese soldier transferred to the PI, where your friend's father "liberated" it.
This happened with a lot of Dutch M1898/M1911 cutlasses when the Japanese captured the DEI armories. They removed the basket guards from them to make them "more Japanese-like". I have one of those bring-backs in my collection.