Michael,
If nothing else, this surely hints at a strong line of cross cultural influences, and while we may never know the exact point of origin, this thread makes of good point of the sword being found outside of what is traditionally thought of as "Moroland".
I think these cross cultural ties and trade offs are one of the most interesting aspects of Indo-Malay weaponry...you see it is kerises, in swords, etc. Just when you think you've seen it all, something will pop up to surprise you and fire up the imagination.
Even the barong Artzi pictured likely had its
naga motif "imported" from elsewhere, as it is not a common motif in Moro weapons.