I think you have done well again Fernando!
I would give Ariel a high grade in his assessment of this tulwar (if I were an Indian specialist
The term 'Delhishahi' if I am not mistaken derives from the Pant typology on Indian hilts ("Indian Arms & Armour" Dr. G.N.Pant, 1980)and this hilt may be considered by that term using that reference. While the term may suggest Delhi as the region for the origins of the hilt form, the actual categorization of tulwar hilt forms by region remains unresolved, and Dr.Pant's work remains an important benchmark for future studies. The book itself I still consider a most valuable resource for the comprehensive data it contains on Indian weaponry.
I would agree that this is likely a late 18th-early 19th c. tulwar probably Rajput and most likely from Rajasthan regions. I am inclined to doubt that the blade is wootz, and agree completely with Lew, leave the patination alone.
The incised motif is indeed often seen on hunting weapons (shikargaha) with images of animals , and figures of the Hindu pantheon are often on blades in low relief on sacrificial weapons. While this does not appear to be such a weapon it may have been intended as a court or parade weapon, but the floral /vegetal motif is unclear. Botanical symbolism was key in varying application in Hindu symbolism and is beautifully described in Robert Elgood's "Hindu Arms and Ritual" , so perhaps closer analysis of the depictions on this blade might reveal more.
Does the motif only appear on one side of the blade Fernando?
Best regards,
Jim