Although the word appears to be Middle English no precise equivalent can be found in the OED or the MED. As the context confirms, the root is most probably Old English qwice (‘couch-grass’) from Germanic quick a. (‘endowed with life’), but the -el suffix is of uncertain origin. A similar unexplained element is present in the English synonym quicken (See OED etymology of quicken n.2, Third Edition, December 2007).