The Model 1840 noncommissioned officers' sword was adopted in 1840. Based primarily on a sword used by the French Army, the model 1840 NCO proved somewhat heavy hilted and ill balanced. For over 70 years, it was widely used by the Army; today its usage is restricted to ceremonial occasions. The sword had a 31-inch blade, a cast brass hilt resembling the more expensive wire-wrapped leather grips, and a leather scabbard rather than the steel used by cavalry troopers and officers.
Model 1840 army noncommissioned officers' sword Wikipedia
It was carried by sergeants during the Mexican–American War, and the American Civil War it was worn either on a white or black baldric or with an Enfield bayonet frog. A shorter version with a 26-inch blade was carried by musicians, this was called the Model 1840 musicians' sword. NCOs of the rank sergeant and above were to carry it. During the Mexican-American War, it was more likely to be carried. It wasn't always issued to volunteer regiments during the Civil War. The sword replaced the sword more commonly known as the Model_1832_foot_artillery_swordwhich was used by both the infantry and the artillery regiments from 1832 to 1840.
The primary contractor for the production of the M1840 NCO sword seems to have been the Ames Manufacturing Company. The weapon was made with a blunt edge as it was intended for stabbing rather than slashing (as in the case of a curved cavalry sabre). It was the main weapon of standard bearers (along with the Colt Army Model 1860 and Colt 1851 navy revolver) and hospital stewards, as well as a secondary weapon for infantry NCOs. The sword was also used by the Confederates who captured many after seizing state arsenals.
There was a variant of the M1840 without a handguard called the musicians' sword which was intended for use by musicians as a personal defense weapon.
The M1840 has had a long service life, seeing frontline service from the Mexican War until the Spanish–American War. In 1868 the ordnance board recommended that no more leather sword, or bayonet scabbards be purchased, so after the leather ones were used up, a black Japanned steel scabbard was substituted, along with a new pattern leather frog. It remained in service as a ceremonial weapon until general orders No. 77 dated August 6, 1875 discontinued its use. A modern version of this sword with steel scabbard is currently permitted for wear by US Army platoon sergeants and first sergeants; in practice it is rarely seen outside the 3rd Infantry Regiment (the "Old Guard") and honor guards. Some army NCOs have this sword and wear it for social occasions, regardless of duty as a platoon sergeant or first sergeant.