Hi Steve,
Another good find! You're doing well, these aren't common.
I'm suprised that there aren't any replies, so I'll come in
The construction of these is very much like Katars.
In fact the grip is reminiscent of a Katar grip-bar.
The one I've pictured has some striking similarites. Central ribbed blade with incised simple pattern at top, inserted into steel hilt. The blade on the Katar is wootz, not the finest though.
It makes me wonder if the occasional curved Katars have Chillanum blades?