The one thing that everyone knows about Gilles de Rais is that, at the most lurid moment of his confession, the Bishop of Nantes veiled the crucifix out of shame. It is a set-piece of several biographies and novelisations.
J-K Huysmans describes it thus -
He seemed to see nothing, hear nothing. He continued to tell off the frightful rosary of his crimes. Then his voice became raucous. He was coming to the sepulchral violations, and now to the torture of the little children whom he had cajoled in order to cut their throats as he kissed them.
He divulged every detail. The account was so formidable, so atrocious, that beneath their golden caps the bishops blanched. These priests, tempered in the fires of confessional, these judges who in that time of demonomania and murder had never heard more terrifying confessions, these prelates whom no depravity had ever astonished, made the sign of the Cross, and Jean de Malestroit rose and for very shame veiled the face of the Christ.
(from Là-Bas)
It was a moment of high drama.
And it never happened.
Gilles de Rais is a magnet for myths and this is one of the most persistent. There is no reference in the record of his trial to Jean de Malestroit veiling the cross. The biographies that mention it do not cite their sources - even Emile Gabory, who was a serious historian and gave proper citations for everything except this claim. There is an similar incident in the Bibliophile Jacob, but in his account the cross was covered by Pierre de l'Hôpital so that Henriet could give his testimony without inhibition.
The veiling of the cross is a myth and it seems to have been invented in its usual form by - J-K Huysmans! Who was writing a novel and not a factual work and may be forgiven for adding a little colour to the dry bones of the trial record and playing fast and loose with the Bibliophile's already fictional version. There is no contemporary account that includes this touching little scene and no reason to suppose that it is anything but a piece of novelettish whimsy. The genuine historians who have slavishly disseminated this fairy tale have no excuse for their gullibility and lack of research.