For this achievement you must have all four weapon slots filled with either purple or orange weapons, and the Shield. Oz Kit, Grenade, and Class Mod filled with purple or orange.
This achievement can only be unlocked after the mission:
because after completion of that mission you earn your 2nd Weapon SDU.
I got this achievement by joining ShiFt and using some shift codes to gain access to golden keys. Follow
Borderlands 2 ShiFt Codes on facebook or DuvalMagic or twitter.
You can use your codes in the "extra" tab in the main menu, or at the ShiFt Box in Concordia! Once you use your codes you can redeem them at the ShiFt Box by going to the second tab. If you use your keys on the Golden Key box you will be guaranteed an purple something!
If you cannot get a Purple Oz Kit, completing the mission "To Arms" will net you a Orange Oz Kit.