Hi Norman,
You are right in noting that the kirach is supposed to be not entirely straight, a slight curve toward the tip. Terminology in Indian swords in particular among ethnographic forms can sometimes be remarkably confusing.
In my understanding this may probably best be considered a sukhela as you have rightly suggested. While the term itself also has applications to a low carbon type steel used in India and often believed associated with these, it primarily refers to a straight bladed sword. Apparantly these straight bladed swords are highly regarded as representation of authority, in essence, a 'sword of state' and carried by court officials, awarded to soldiers in high esteem and honored and other similar stations. The straight bladed sword I believe in Marathi is termed 'dhup' but obviously thier swords were khanda (or firangi) and pata which had straight blades, so it is puzzling to consider how that would apply.
This is of course an Indian made blade, and you have acquired an usual and interesting sword.
It would be interesting if someone could post a kirach so we might compare these, as well as better explain the dhup term....Jens?
All the best,
Jim