www.gatling-gun.com/CivilWarNCOMilitiaKnight'sHeadSword.htm
Here is a similar pattern known as a NCO militia sword. BTW, if you just hit KKK sword under google (I won't post the site here out of respect), you will see similar swords to this one. This one might be an early pattern, but the Ames marking is obviously spurious, with the letters poorly punched. Don't know why anyone would want to fake that marking? Ames made most of the CW UNION swords, after all!