Huge yatagan blade, totally brass-made hilt and crossguard, like in French M1840. Markings only on the hilt. This is the first of long line of American saber or yatagan bayonet. It seems not obvious, but the 1841 yatagan had been adopted for 1841 musket in 1858, after it ‘s modification for .58 caliber.
There are at least two scabbards for this bayonet, both hard to find differing in the shape of frog fixation and lower brass tip.