Treyarch has just announced a Black Ops 2 Double Weapon XP Weekend starting August 2nd at 10am PDT and will end August 5th at 10am PDT for all platforms.
2xXP Weekend might be over, but we’ve still got 2x Weapon XP ahead! It starts this Fri at 10am/PDT and will run through Mon at 10am/PDT.
— Treyarch Studios (@Treyarch) July 29, 2013
This is in celebration for the upcoming release of Vengeance DLC for PS3/PC on August 1st.