Lee hit the nail right on the head. The seki stamp denotes a mass produced blade. During WW2 these blades had more symbolic significance than they were actually used for combat. They helped establish a psychological connection between the soldiers and their samurai ancestors whose single purpose revolved around warfare.
That being said, it does still have some value to the right person, just not as much as a traditionally made nihonto or shinken. Certainly WAY better than any wall hanger out there in terms of history and even construction.