While clearly of 'smallsword' style, this example seems to be a court or dress type piece intended to represent the 18th century smallswords in a neoclassic rococo style. In England there was apparantly some inclination toward what was termed Louis XIV style in art, furnishing etc. during the 19th century, and this cast sword seems that it might fall in that category.
The elaborate detail, unusual structural designs in the pas d'ane and the knucklebow do not correspond to any smallsword hilts carrying such designs in either Aylward ("The Smallsword in England" ,1945) or Norman, "The Rapier and Smallsword" (1980).
The blade also does not seem to correspond to typical smallsword blades of the 18th century, and its cut down status seems doubtful as any type of left hand dagger, as those fencing techniques were long gone even in the smallsword period as a rule. It is interesting though that it seems many broken swords were indeed made into knives with thier original hilts left as is.
A case in point were the huge M1913 Patton swords issued to U.S. cavalry, which actually never saw combat aside from some speculation concerning limited appearance in WWI combat regions. These were placed in stores with disbandment of mounted cavalry units, but later during WWII, many of these had the blades cut down but left in the huge steel bowl hilts to be used as combat knives.
"If ya dont waste nuthin, you dont want nuthin"
-Benjamin Franklin
All the best,
JIm