Mighty Ferret  . That was the short form of her nickname for  O Mighty Whey Faced Ferret  , to which he and Astoria had laughed at. At a time when there was little enough to laugh about as the blood curse ravaged her weakened body. He had just stuck with  Weaslette  but they both knew it hid numerous adjectives to describe her brilliantly focused heart and mind. And her annoying Gryffindor traits.