I search for this and I did not find any post regarding this exploit.
This is my first contribution post
Alright to get this achievement, you should at least have 4,000 conquest points, meaning that you can get this achievement within 2 weeks of reaching maximun level,
1. Get at least 4,000 or (enough to get to upgrade your 2h weapon if 2h user, Remember don't upgrade weapon till step 5)
2. Buy conquest gear (epic gear) from the vendor at Kun-Lai Summit (horde) should be the same for alliance.
3. Buy Malevolant Gladiator's gear, equip it, then refund it.
4. Do step 3 untill you have bought and equipped every slot (careful Right Ring and Left Rings counts meaning that you should buy 2 different rings, and I think works the same as for Trinkets)
5. Lastly get the WEAPON, go to Orgrimmar/Stormwind or Shrine of the Two Moons/Seven Stars and upgrade the weapon to 2/2, 1H weapons cost 2500, upgrade to 2/2 cost is 1500 Conquest points. upgraded gear cannot be refund it!!
5.1 optional, alternative you could get the weapon from Inscription is called Serpent Staff I believe, but is only for staff users
With this exploit you will get the following achivements aswell *only if you haven't earn them yet*
Epic
Catacylsmic Epic
Superior
Cataclysmic Superior
Mystically Superior
It works same way as for Valor Points, only that Valor gear have restrictions and could take a lot to get this achievement thru Valor.
Get epic achievement folks
Best regards!
EDIT: Exploit or "not" as many people claims, you shouldn't be walking with the achievement with only 1 equipped epic weapon in your toon and every other slot green/blue never intented to be that way.