US Model 1860 Cavalry Saber
“About 1860 a light saber was introduced for cavalry. in this new model, which did not immediately supplant the heavy saber, the blade was reduced in width, and the entire weapon was lightened. The exact date of this change is not known, but the light saber is mentioned in the Ordnance Manual of 1862, and most of the sabers of the Civil War and later were made of this pattern. The date 1860 has traditionally been given for this change and is used here, although one or two specimens dated 1859 have been encountered.
The light saber can quickly be distinguished from the model of 1840 by the lighter blade with its rounded back and by the shape of the grips, which have a swell in the center. In all other characteristics, however, the light cavalry saber is like its predecessor.”
–Harold L. Peterson, The American Sword 1775-1945 (1965)