In Black Ops 2 each weapon gains experience and it can be used to unlock attachments and other customizations. In previous Call of Duty games Prestiging gained you a new rank logo, but you lost everything that you've unlocked and started from scratch. Lucky for gamers, David Vonderhaar has confirmed that after Prestiging you won't have to start from scratch, instead you'll be able to continue where you left off.
David Vonderhaar: "Weapon levels are given after unlocking a gun that was leveled up on a past level progression. That's what we call NAB. Not a bug. If you Prestige and unlock the gun, you'll pick up right where you left off."
Vonderhaar also previously confirmed that you can carry over one weapon after Prestiging, so there's no need to reach a certain rank to unlock and use your favorite weapon(s).