A Strange Tulwar

[Blade]

Hello!
I've got this tulwar, which my father bought on a trip to nepal.
The seller claimed this piece is very old.

The blade has a straight totally unsharpened segment followed by a deeply curving blade (which has an edge that has gotten dull over the years) . it has markings on both sides, a moon on one, and a sun on the other. it was fully covered with rust, and that's how it looks after some cleaning.

It's surprisingly well balanced, the unsharpened part fits well for gripping the blade with the left hand.

I have searched the internet and haven't found anything that looks like this sword, can anyone identify it? help me date it or determine it's authenticity?


thanks
Yaniv