My Dad recently gave this to me and I thought it was worth sharing. He served in the US Navy from 1948 - 1956 as a Boikermaker. He had friends all over the ship (including the armory). This was before e-mail/internet, and the only way to communicate was by hand written letters. As the story goes, he made this over about a weeks time while he was on watch in the boiler room of the ship. Evidently my Mom wrote him alot of letters, and he wanted to be able to open them quicker!
Here are a few pics of a letter opener he made.