"Ancient Roman Iron and Bone Sword (a Spatha). Early to middle 3rd century AD. Recently authenticated and appraised. Found in England. 27 3/4 in. in overall length - blade is 21 3/8 in., the hilt is 6 1/4 in. - max. width of the blade is 1 9/16 in."
If it is on an auction site these days you can pretty much guarantee that it is a fake. The internet makes it too easy for people to learn the true value of what they are selling and the chance of finding a "bargain" is almost zero these days. If you want an authentic antique then you need to go through licensed dealers and auction houses, or buy it illegally though the black market and take your chances.