Go to Lord Saladin (top of tower while event is active) and buy it for about 1000 glimmer. You have to be Iron Banner rank 1 (at least you did last time) and this took 4 wins in the Iron Banner playlist. My Cousin (Hunter) bought the cloak, and I (Titan) purchased a pretty cool mark. However, the rewards aren't permanent, so if you don't have much glimmer and save it until you know what the permanent "rewards" are that Bungie keep promising...