The next part of Bungie's Guides by Frankie is up at Bungie.net. This one covers Dual Wielding. There's a list of weapons that can be dual wielded, including the plasma pistol and rifle, the human pistol and SMG, the needler, and an as-yet-unrevealed Covenant weapon. You can wield any combination of two of these weapons in either hand. The article goes into quite a bit of detail, describing the pros and cons of various weapon combinations; Frankie notest that twin SMGs are especially effective against Drones, as the kickback on the weapon actually helps track targets flying overhead.