Hey there, when your Titan finished 'Home II' it unlocked 'Queens II' for all characters, however, the Titan MUST earn the Queens II reward before that becomes available to alt characters. As of yet your Titan has not played that mission, and until they do, Warlock and Hunter can play it but not get the reward. Play Queens II on the Titan, then replay it on Warlock and Arcane Needle should unlock for the Warlock.