"Graendal: One of the Forsaken. Once known as Kamarile Maradim Nin-dar, a noted ascetic, she was the second of the Forsaken to decide to serve the Dark One. A ruthless killer, she was responsible for the deaths of Aran'gar and Asmodean and for the destruction of Mesaana. Her present circumstances are uncertain."

Why would be it be mentioned in the same sentence that Graendal is a ruthless killer if she hasn't kill directly any of the Forsaken mentioned in the second part?

Also if Graendal has used Slayer before to kill a Forsaken, why didn't Moridin mention it when he lent her his services to kill Perrin? Why wasn't there a reaction from her, something like "Yes, Slayer has proven very useful in the past".