With Patch 2.4.2 the crafter only blacksmith weapons like Dragonstrike, Wicked Edge of the Planes and Blazefury become dual wieldable. They will lose their current unique and mainhand only status.
While this might be nice for players pre-Hyjal, blacksmithing is still not an option for Rogues/Shamans who are beyond Tempest Keep. It is quite ironic that most professions got some high end crafter only items with the introduction of Sunwell Plateau with the exception of Weaponsmiths.
The most exciting innovation in blacksmithing will be the ability for blacksmith players to make epic quality items that only they can wield. A master swordsmith will be able to forge a special sword for him(or her)self, and a suit of epic armor awaits the master armorsmith. The smith will be able to upgrade these special items, so they will always be a solid item for the smith to wear or wield no matter what stage of the game he or she is in. To allow everyone to take advantage of this, blacksmith specialists will be allowed to change their focus in The Burning Crusade.
Excerpt taken from the official Homepage.
With the introduction of Hyjal and Black Temple 1 year ago these solid choices for a Player have become outdated by far. I’d like to see a new upgrades to these Weapons that include Hearts of Darkness and in the latest Version Sunmotes to craft. At least the dual wielding of crafter weapons is nice for beginner Shamans.
taken from MMO-Champion.com
The procs do apparently stack and not refresh each other, including Dragon Spine Trophy. Found this picture here:
NOTE: The stacking haste buffs did not make it into Patch 2.4. Thus I am no longer sure if it is worth it to dual wield 2 outdated weapons over the badge fist weapons. The Dragonstrike was a nice alternative in TK, but with the introduction of Mount Hyjal, Black Temple and especially Sunwell Plateau they have been way outdated.