as someone mentioned that they have not seen evidence of native american swords, i note that the aztec used the macahuitl, a flat wooden 'sword' edged with obsidian, there have been notations by the spaniards that it was capable of beheading a horse.
northwestern tribes have examples of copper daggers, north american aztec and incas from the southern americas were using metal tools, but obsidian was so much sharper and easier to work that chipped stone use carried on into historic eras. without the infrastructure to find,mine, prepare, smelt, cast, and finish metal, stone can be chipped by just about anyone trained for a short time.