Ian, the pommel resembles more closely an uncircumcised penis than a flower, but for me that is no clue.
Alan, we've discussed nomenclature before and I concur with your view. My interest is far less in what this sword is called and more in its regional and ethnic origin and function.
The idea that this sword might be related to a Naga Kabui weapon used for dancing was the first to occur to me when I saw it for sale. Please see the pictures attached - two depict my Kabui dao and the third is a dancer with a substantially smaller Kabui dao. My Kabui dao is a two-handed weapon of roughly the same size and even greater heft as the mystery sword we are discussing. The overall length is 25 1/2 inches with a 16 inch blade. Also, the Kabui dao is sharp on the curved edge, not the straight edge like our mystery sword.
I consider Assam as fertile hunting ground for identification of weapons that don't seem to fit the surrounding regions very well. Consider: The Kabui are one of the Naga tribes who reside in the area around Manipur. The dominant sub-tribe is called "Rongmei". In Manipur, "Zemes" and "Liangmais" together were recognised as "Kacha Naga", while the "Rongmei" and "Npuimei" as "Kabui".In the Brahmaputra valley and nearby are found other tribes such as the Kuki, Kachar, and Khasi. [See references below]
Much blending and cultural interchange has occurred since British occupation, but they retain distinct identities. The Kuki tribe is known to decorate their weapon blades with copper and brass and this may have, for example, influenced the decoration of my Kabui Dao.
This has led me to the idea that Assam deserves more attention; there is scant information available regarding edged weapons of the region.
P.R.T. Gordon, The Khasis
. Available from Project Gutenberg
Rongmei Naga, Wikipedia