Here are a few NCO swords being worn by Sergeants in the 25th NY, a regiment that, by all accounts, scoffed at regulations at every level of command, from top to bottom.
While not the best weapon, keep in mind that a Sergeant can, at any time, have to step up to platoon/company command, and other than the fact that you'd be shouting orders and standing in a new spot, a makeshift badge of rank is there at your hip if you need it to identify yourself to your men as their new boss.
Marc A. Hermann.
The Daybreak B'hoys.
Liberty Rifles - Hardtack Society.
Oliver Tilden Camp No. 26, SUVCW.
Descendant of Pvt. E. Hermann, 45th PA Militia - Capt. Wm. K. and Lt. Geo. W. Hopkins, 7th PA Reserves - Pvt. Jos. A. Weckerly, 72nd PA Infantry - Pvt. Thos. Will, 21st PA Cavalry.