Silver mounted Georgian hanger.

[Gavin Nugent]

I think it is a nice find and most unusual that the hilt is bone with what appears to be horn spacers all with silver fitings.
There must be something about it to have these features, I do not know why but am hoping others can say with some further certainty.
What I can point you to is the book, "the American Sword 1175-1945" by Harold Peterson.
On page 62, plate 56, this piece sports the similar knuckle guard, similar carved hilt arrangement, lions head and curved blade with the fullering arangment that yours shows and the guard is described as having incised lines as yours does too.
On page 212, plate 172, although in silver, the lions head is of higher quality as is yours, but it lacks the knuckle guard and the blade differs in the fullering arrangment and the silver mark also differs.

Gav