Andrew,
These markings of what appears to be a sunburst seem very much like similar markings it seems I recall seen on some Cham weapons, or of SEA provenance. While reviewing notes here to see if I can add anything that might associate with anything Indian or European, I am wondering if you, Mark or Ian have similar markings catalogued.
This really is a magnificent and unusual kirach Rick !! Even more so with its clear transitional character that really embodies the diffusion of these weapon forms in India. I agree with Jens that there seem to be quite possible Sikh associations here, and more research will hopefully support that. It has always been interesting that the sacred sword of the Sikhs was of course the khanda, with Hindu baskethilt, while the sword of choice used by them in combat was typically the tulwar. Here we have a hybrid of both. Fascinating!!!
All the best,
Jim