If you head over to the House of Wolves page and scroll all the way to the bottom, you'll notice the 7th screenshot has some Guardians toting some huge rocket launchers. The kicker being they also have their standard issue heavy weapons on their backs too! So either we get a primary RL or it is some sort of "Sword of Crota" pick up. I like the first one with, with my Titan and his Rocket Sleeves on.