Where to get new exotic armor (from previous DLCs)

[thin garden]

Sorry for newbie question, I left the game after final shape. Lets say I want to unlock Speedloader Slacks. I have already completed Lightfall campaign on launch and did not choose them as reward. I thought lost sectors will give them but the reward is exotic engram, not legs.

[narrow forge]

use the engrams at rahool, cost of 1 exotic cypher+1 engram lets you choose the exotic you want

[thin garden]

Thanks!