This sword is one of the most misunderstood short swords I have come across. Based on observation rather than any real knowledge of its manufacture, it appears to be made up of a hilt of a particular style and a blade. The blades vary widely while the hilt keeps the same design but may change in size and decoration. From the best that I can tell they are all fraternal swords.
The Civil War was the spark that ignited a huge interest in fraternal organizations. It has been suggested that the military experience fighting in the war caused a desire for male organizations and these organizations were formed from mutual assurance societies whose members would help look after members' families after the member passed away to purely social organization. There were also the Masons and religious groups who wore uniforms, held meetings with secret rites, and carried swords.
If you look in the book, The Ames Sword Company Catalog, at sword number 331 you will see the hilt illustrated, although, based on the scabbard it is paired with, the blade seems narrower than yours. It is described as, "Roman Sword, Black Leather Scabbard… Brass $4.00, Nickel $4.70, Gilt $5.50." Swords that were of military regulation shape and size were listed as military swords.
I can't find the right sword book, but one author listed it as a post – Civil War naval cutlass dating to the 1870's. This was because there are a number of these hilts on surplus bayonet blades that had been originally contracted for and accepted by the U.S. Navy in the 1870's. Some have suggested that this version of the short sword was created by Bannerman out of surplus blades and his own cast hilts. In fact the Bannerman theory is always attached to any group of swords that have the same cast brass hilt for which there is little information.
There are a variety of blades matched to various hilts in the study collection I use, but I don't have the camera resources at the moment to take pictures. Maybe I can come up with something.
Since these swords are so poorly understood, they are frequently identified as Confederate or, perhaps, European.