The Collaborative International Dictionary of English v.0.48:

Wanion \Wan"ion\, n. [Probably for OE. waniand waning, p. pr. of
   wanien; hence, used of the waning of the moon, supposed to be
   an unlucky time. See Wane.]
   A word of uncertain signification, used only in the phrase
   with a wanion, apparently equivalent to with a vengeance,
   with a plague, or with misfortune. [Obs.] --B. Jonson.
   Latimer.
   [1913 Webster]