Note the splice in the knucklebow on the Ames Staff & Field Officer's and Foot Officer's swords. There is an exception found on the Ames Mounted Foot Officer's Swords. These have metal scabbards (for obvious reasons) and a single piece knucklebow/guard.
The M1850 Staff & Field Officer's Sword was inspired by M1845 French sword. The primary difference between the Staff & Field Officer's Sword and the M1850 Foot Officer's Sword lie in these details:
"It is well that war is so terrible, or we should grow too fond of it"
General Robert E. Lee