It is a forged blank for the M1905 bayonet that was not finished, and probably either modified by one of the workmen during the war or by someone afterward. Probably not finished (although several cuts have been made) because it failed a dimensional test at some point. Looks like it could probably be fitted with grips and someone may have done so at one time and made a "knife" out of what was otherwise a piece of junk. Markings were one of the last things that were done which is why there are none.
It looks like the blade was considerably thinned, probably to reduce weight and make a sharper edge.
This is a forging that has not progressed as far as yours, only the very first finishing steps were taken.