Hi Bandook:
Very interesting piece. The general shape looks like a Moplah/Malabar/Mysore/Kerala "chopper" that has been discussed here before. Here is an old thread that discussed some of them --
http://www.vikingsword.com/vb/showthread.php?p=11397
Incidentally, these choppers could be sharpened just on the concave edge or on both edges.
Ian