The word "execrable" (which has the same meaning in English) is never used for a title of a movie .Perhaps the director wanted to warn the audience ,to urge them not to follow in his heroine 's steps ;and maybe to clear his name because of the censorship ;which did not prevent the Office Catholique Du Cinema from forbidding their flock the movie.
Being born a witch's daughter did not bode well for your future in the Middle Ages .However much Guillaumette tries to stay on the straight and narrow with a little help from a priest she visits ,what's bred in the bone comes out in the flesh.On the very night of her wedding,the infamous girl leaves the conjugal bed - one should say that her hubby could easily be her grandfather- to attend (and take part in) an execrable sabbath;this long sequence with topless women provoked an angry response from the well-meaning people ;it was rather risqué for the time.The director astutely allowed some doubt to remain about the reality of the event and thus (modestly) predated Roman Polanski's own ceremony in "Rosemary's baby" .
Too bad the director was not really up to scratch cause there was an original subject;too bad highly talented Germaine Kerjean disappeared after ten minutes ....nothing here to match Val Lewton's productions ,just a curiosity lost in the French cinema of the late forties .