I've been thinking about that scabbard and went back to a book I have; Warren's The Sulu Zone .
In the later deacdes of the 19th century the Sultanate of Sulu had a population of roughly 200,000 souls .
Many of these people were taken from the northern islands by raiding parties .
The Sultanate needed manpower for tripang, pearl and shell gathering .
Many of these captive workers assimilated into Sulu society over time .
I don't think it would be too much of a stretch for this scabbard to be contemporary to those times .