Hi Joe,
Extremely unusual piece, the blade appears to be a ram dao blade from NE India, border regions of Nepal. The use of the oryx horn, resembles the parrying weapons of the Marathas, the joined stag horns known as 'madu' (also maru, Pant p.184, "Indian Arms and Armour", New Delhi, 1980).
I cannot say I have ever seen such a version of ram dao, and the blade is extremely nice with the chiselled spine. This exact blade shape appears in Pant (op.cit. p.68, fig. 144).
These hybrid anomalies are most interesting, and reflect the amazing cross cultural diffusion of weapons and thier components via trade networks. The blade or perhaps, the entire weapon is carried to another location, then often remounted in either local style hilt or sometimes customized at the whim of the individual. I have seen so many weapons with completely atypical hilts its hard to even describe them all
Nice looking item!!!
All the best,
Jim