So as I was exploring the wowwiki site reading up on the Titans and their strengths I came across this page
It describes the ultimate Titan weapon that is sentient itself. It was originally wielded by Sargeras before he turned evil but split itself into two pieces in order to prevent the Titan from wielding it's full strength (remember it's sentient). If the two pieces are brought together they can supposedly be remade into the original weapon. This, however, can only be done with somebody who is non-evil. This could possibly make a very nice final legendary at the end of WoW.
It's a Titan sword! It's two big for us!
Well yes BUT it has already shown that it has some kind of shape-shifting ability as it was able to split itself into two fragments to prevent Sargeras from wielding it's full strength. Who's to say it won't deem us worthy and become a weapon we can wield?
But if it's a sword I can't use it and in MoP we all got legendaries!
Once again shape-shifting sentient sword. It will most likely have a different weapon type depending on the class and obviously a different effect per role. If Blizzard does decide to continue on with the "every gets a legendary" idea then this would be an easy way to explain how this weapon can be used by anybody.
Those are just the ones I thought of off the top of my head. What do you guys think about this?