An interesting refurbished piece indeed! I can't add anything to what the others have already mentioned. There is one thing, though. Are we sure this brass hilt pattern is from a French example? The American patterns from the time of the Mexican War up to the Indian Wars heavily copied the French patterns, m1840 Cavalry sabers, m1860 infantry, m1870, etc, etc. I am no expert on CW types, but I've seem them in catalogs.
If you identified the hilt as being an American pattern, the game is afoot! As you probably know, the Confederacy were non-industrial and during the conflict, were in dire need of weapons, materials, blacksmiths to fashion everything! The 'rebs' made do with what they had, refurbishing old sword parts with other hilts, blades, knuckle bows. One only has to look at so called 'Dog River' swords to see the plethora of odd examples present. Indeed, some of the finest Confederate swords were made by both German and French imports!
So...you might (and I do mean might in small print
) have a Confederate cavalry sword, Blockade Runner's cutlass, etc. Exciting thought, but without much research and a darn big helping of luck, it is just a weak theory...