As an interlude in proceedings I have unearthed a documented list of items said to have been removed by the Governing powers of the day ruling Sri Lanka. The period covered is extensive thus I searched there in case an early Kastane could be discovered.
On page 15 of this document http://unesdoc.unesco.org/images/00...87/038748eb.pdf
I found IM 10/19/10 held at The Britich Museum the hilt portion (incomplete) of a sword Kastane described as ; Pommel of Ivory with Simha head, Grip curved with typical scrollwork, Vaka Deka Motif and floral bands.
Said to have been presented by King Parakrama Bahu V1. 1415 TO 1467 to a chief of the Weerasinghe family . Very much weathered. Parts missing. Sold for 3 Pounds in March 1910.
There are other swords and weapons but this one is particularly important as it predates the Portuguese. (I dont know if these are still abroad or have been returned to Sri Lanka.)