For the weapons, you'll have to hit up Karazhan, which has quite a few items available for transmogrification. Despair is one that requires the most patience. You have to get the Romulo and Julianne theatrical event, which is random, and you have to have it drop, which is random. If you have the weapon already, hit up the instances listed below to acquire the rest of the set. :p
Head: Ruby Helm of the Just, The Blood Furnace Heroic, Keli'dan the Breaker.
Shoulders: Pauldrons of Swift Retribution, Mana-Tombs Heroic, Nexus-Prince Shaffar.
Chest: Breastplate of Righteous Fury, The Slave Pens Heroic, Quagmirran.
Waist: Girdle of Gallantry, The Underbog Heroic, Ghaz'an.
Legs: Ornate Leggings of the Venerated, The Shadow Labyrinth, Blackheart the Inciter.
Feet: Ornate Boots of the Sanctified, Shadow Labyrinth Normal and Heroic, Ambassador Hellmaw.
Wrists: Bracers of Just Rewards, Hellfire Ramparts Heroic, Watchkeeper Gargolmar.
Hands: Gauntlets of Vindication, Mana-Tombs, Nexus-Prince Shaffar.
Main Hand/Off Hand: Despair, Karazhan, Julianne from Theatrical Event.