I have located an lithograph from 1823 that includes a knife somewhat similar to the ones pictured above. It is just a vague clue at this time - but time will tell. The knife is pictured on the person of a native hunter from Guam. Guam had no native metal resources and no pre-European metal's technology. However,had become a standard import, and by the early 1700s we know that the Spanish Governor was advising his superiors that the natives had been provided with all of the axes, swords, and knives that they could use, and that inventories of these goods were stocked in excess of need.
As with most native cultures encountered during the period, the original population was quickly decimated by desease and war. The pre-European population of approximately 50,000 had been reduced to somewhere around 5,000, and these were mostly women and children. The Spanish actively repopulated the island by importing people from their colony in the Phillipines. By the 19th century these populations would have been well integrated. That might explain the odd feel of these knives.
n2s