Riddle: Civil war antique collector who is told by his neighbor it is fake. Why is it fake?

There is a man who has been steadily collecting civil war antiques for years. There is a new antique store that newly opened up downtown. The man arrives at the antique store and sees a sword. On the beatuiful sword there is an inscription with the date of Bull run on it. The sword was dedicated to those who died in the battle. the man asked the storekeeper how legitimate it was. The storekeeper responded in saying that it was infact dedicated to those who perished and that it is an amazing weapon. he asks for 2500 and the man buys it. Later that day excited about his new purchase the man asks his neighbor to come in and admire the sword he just aacquired. His neighbor, a regulaar guy who knows little of the civil war other than that in his high school cles( well educated guy) immediately recognizes that its fake. Why?