Class specific armor is bought from vendors in Katta Castrum using Phosphenes. Each event unlocks a slot and drops roughly enough currency to purchase two of them, though they can be used to purchase any slot you have unlocked. For example, the 6th Event unlocks Legs and drops 800 Phosphenes. This can purchase one set of legs, a head, and a wrist or 4 gloves and 2 wrists, or any other combination. The currecy is tradable allowing guilds to decide exactly how they want to distribute it.