I read Graendal's ownership-of-an-angreal-from-Mesaana scene as an indication that at some later point she would need to do something powerful enough to require an angreal, and the hastily-written story of her having one from Mesaana was to be the literary justification of why she had it.

Then Graendal was killed in punishment, so now presumably her angreal is back up for grabs. Someone in another thread said that Graendal was mindtrapped, and although I didn't read the scene that way (you have to go to Shayol Ghul to be mindtrapped, iirc, and the storyline ended in her palace, so who knows), but either way, it's a loose angreal floating around out there.