Thanks a lot for your thoughts, Gentlemen.
I am usualy skeptical when it comes to relating (my) findings with origins like the American Revolution, for obvious geographical reasons. This wouldn't be the case if or when i acquire them in international sources, through the Internet; but this one, as many others, was bought locally, from a street fair vendor.
Concerning the blade ridge, there is in fact one in this example, but so tenuous that it practicaly doesn't show in the pictures.
Definitely the base of this blade once had a different format; looking inside the present socket we can see a section of the original one, with about an inch length, cutt off and welded to the present conical rimmed tube.
So it could originally have had langets or, giving wings to imagination, could have had a handle, like a short sword. I know this is not so plausible; just fell like talking nonsense
.