Rick, considering their geographic and cultural proximity, I would surmise that the associated meanings of such markings from the realm of the keris world must have carried on at least to some extent in the mindsets and work of Moro smiths.
Perhaps entirely unassociated except by the nature of the medium of forged iron, iron blade inlays are also frequently observed in European Migration Period and Viking Age swords (even the sword in the logo at top of this page has one!) and such inlays do include swirls. I have just finished reading a most engaging doctoral thesis on iron inlays in late Iron Age Finland -
Marks of Fire, Value and Faith Swords with Ferrous Inlays in Finland during the Late Iron Age (ca. 700–1200 AD) by M Moilanen (2016) that seriously ponders the significance of such inlays (and the author and his university have generously provided a
pdf of the entire book!) Some of these marks may well have had talismanic significance to the maker or user while others may have been a maker's mark or 'signature' or they may have been applied as an otherwise anonymous testament to the technical proficiency of the smith. Also, it is noted that peoples everywhere from the beginning have liked to decorate their tools and other possessions.
I am going to resurrect
an old thread of Lew's to show another similarly very subtly curved 'straight' kris that features iron inlays.
Kai, I have noted your interest in a top view of the gangya and added it to the photo queue. Meanwhile, here are the requested close-ups of the base of this blade: