This is a sword bayonet, believed to have been sold to Turkey along with the Peabody breech-loading musket contract; however, it is my contention, these were actually part of a Winchester contract for the 1873 Military Musket.
Overall length out of scabbard is ~28"; yatagan (re-curved) blade length is ~22-3/8". Grips were of black pressed leather, checked for better grip.
Scabbards were of black leather body, single-stitched on the back-side; sheet-rolled-steel throat and drag. Round button head on frog stud, ball finial on drag.
These are very similar to the French 1866 Chassepot, the British 1856 Enfield, and the Danish 1867 Rolling Block sword bayonets.