This quest is not available in game.
Obtain a power source from the most powerful construct you can find in Uldaman, and deliver it to Talvash del Kissel in Ironforge.
You are going to need to find some "oomph" for the necklace, and Uldaman is probably the best place for it, actually. I guess there are a lot of constructs running around in there, yeah? Well, take out the biggest, baddest construct in that place and grab its power source! I am pretty sure I can fuse that source into the necklace.
Without that power source, fixing the necklace will be impossible. Come back to me here to Ironforge when you have it, and we'll get it all fixed up for you!