Silver Ghost

The Silver Ghost is a personal (?) firearm belonging to Leon Scott Kennedy. Almost no info about the gun is actually given in any of the games, but this awesome article about it by ARMS magazine explains it all.

The ARMS article
Despite the entire article being written by a non-CAPCOM employee and the disclaimer saying the article has no connection to story, some of the info for some reason is taken as canon, in particular the name. This is because lo and behold the author had previously interviewed the Resident Evil 4 weapons designer. Although the interview itself is unavailable, some people just sorta assume somewhere in their talk the employee said something that is true about the gun and the writter put that in the article, (in particular the name). So even though there's nothing saying the article is official, or what info used from the interview is official, or what info was even given, some people think that it's just plane unlikely nothing of it is true, like the name. Why would the author make it up? Why would the weapon designer make up his own name for it? Point made.

Project Umbrella's got their own non-official translation for the article can be found on the web somewhere.

True info as far as we're concern
After Ashley was already kidnapped, Leon apparently had time to visit his friend Joe Kendo. Surprisingly enough, he also planned on having enough time to expect Joe to make him a brand new gun before leaving for his mission.

Upon Leon's request, Joe adverts it and suggests for Leon to try a new pilot gun he has been working on. Joe describes it as being an "absolutely brand new Samurai Edge.". However he also prompts Leon to name it. Leon calls it the "Silver Ghost".

The gun originally had the symbol of the United States as the mark on the grip, but Leon changed it his personal mark, a skull. Oddly, Leon never actually applies a skull mark on any of his other belongings. In fact, Leon happens to have a custom designed knife with a dragon on it.

Resident Evil 4
The handgun first appears as Handgun. Leon starts off with this in the game with it. He uses this in all cut scenes so it's probably canon he is stuck with this. With the exception of afterwords where he used the Blacktail for fun to battle a lot of enemies. Probably because it was stronger.

Oddly enough, the Merchant can sell a gun just like it to Leon. The Merchant even has a useable one for Leon in the shooting range. In fact, Albert Wesker also uses one with a Silencer to battle enemies after the main story has ended.

Resident Evil: The Umbrella Chronicles
Actually, Wesker apparently already had the weapon as he uses it before the events of Resident Evil 4 during Umbrella's end. This could have something to do with the fact the gun was still in pilot run. Wesker could have stolen a prototype.

Resident Evil: Degeneration
Leon has kept the Silver Ghost for his mission during Degeneration. It seems to be fully upgraded as he landed an awesome headshot that killed the last boss.

Resident Evil: The Deck Building Game
The gun appears as the Silver Ghost here. Now the name is official!!! Because we know all the card names are official and it was not like they used a lot of localized names right? lololololol

Resident Evil 5 & Marvel vs. Capcom 3
Chris is scene contemplating on using the gun in the very first trailer for the game. In the end he didn't use it. However he is seen using it in Earth-96169. This could suggest the divergence started before he decided not to use it for his mission in Africa.