UPDATE: PC, Xbox One, Xbox 360, PS3, and PS4 players who are 5th prestige or higher have the Gold Knife unlocked, and those who are 10th prestige have the Gold Pistol unlocked now.
Infinity Ward has released details that a brand new Gold Knife and a Gold Pistol are coming to Call of Duty: Ghosts on June 3rd on all platforms.
Gold Knife will be available to those who are 5th prestige and higher in Call of Duty: Ghosts. The difference from the Gold Knife and the regular knife is that it has a faster melee time.
Gold PDW Pistol will be available to those who are 10th prestige in Call of Duty: Ghosts. The difference from the regular PDW and the Gold PDW is that the Gold one is fully automatic.