I shall have to ask at Borgin and Burke's, if I can't find the answer in the Restricted Section of the Hogwarts library, but if that quill wasn't a Dark Artifact of some sort or another, I'll be very surprised. Openly using such a thing at Hogwarts, even with Fudge on her side, was another sign of utter overconfidence. An overconfidence that I was increasingly sure I could prove was mistaken. I had come up with a plan.