The Hatan kavya text “Seethawaka Hatana” written by a warrior who was supposed to have fought in the Great Battle of Mulleriyawela include a narrative in which he refers to at least 5 chiefs who fought with Kasthana swords. this is from Ref B #87....In Forum library.
THE CASTANE was a badge of office for Government clerks (MUDALIERS)..and secretaries not usually a battlefield weapon though it was worn by squad leaders and commanders in battle as a rank marker... but can be viewed in great depth on forum. Please see References above.
The weapon appears to have been in two forms since a battle style may be what we are seeing in the Sendai Museum exhibit and perhaps in the stone carving showing the Pinhao weapon. Thus battle Castane may date to the Portuguese period but following that the sword was only used as above...in the badge of office role.
Most weapons shown here refer to non battle Algerian forms some for use at weddings as cake cutters and none as far as I can make out for battles..They are unrelated as are belly dancing swords.