You're got an excellent point there. Yes, that easily could have been the case. Still, this hanger isn't something that I would imagine the average Singhalese warrior in the 17th century would have wanted to carry. The hilt is in the Dutch taste, the grip in the form of the standing Singhalese lion, the protruding guard a crouching hunting dog, the quillons dragon heads and the blade of typical hanger fashion. These hilt patterns were indeed coming out of Ceylon at the time, but for the Dutch market (thus, the ivory smallsword with the exact same hilt pattern). I know the kastane has some of these specifics, but the blade on mine even has 3 fullers and the blade has been painted/stained with a brown primer, something very common for swords that went to sea. Likewise, hangers were very popular with sailors due to their short working-length.
The diamond pattern on the sword being discussed (and on mine) as mentioned in the past is found on some Dutch "dump" coins of the 18th century, BUT the same pattern is found on early (1st Century A.D.) Singhalese coins as well. Because it seems Shri Lanka and Dutch cultures have intermingled during the spice trade years much as the British/Indian and Spanish/Philippine cultures, I might never get an answer
. Still, I'm not trying to take away attention from this piece to focus on mine, just thinking aloud. Wish someone could post a pic of a Dutch Dump with this marking on it, may shed some light on Dutch markings on swords...