Obtaining the War Af is bound to the job related quests. They start for War (if you're Mrd 30 & Gld 15) at the Mrd guild.

You will get 4 pieces at Level 45 and the body part with the final job quest at Level 50.

Check for further informations: http://forum.square-enix.com/ffxiv/t...tch-1.21-Notes