In Scene 2, Shaw's stage directions refer to the popular reputation of Gilles de Rais as the basis of the fairy tale character Bluebeard:
Gilles de Rais, a young man of 25, very smart and self-possessed, and sporting the extravagance of a little curled beard dyed blue at a clean-shaven court, comes in. He is determined to make himself agreeable, but lacks natural joyousness, and is not really pleasant.
Gilles de Rais was a real French nobleman and military leader who later in his life confessed to being a serial killer of children. He really did work with Joan of Arc before anyone knew he habitually murdered children. He is sometimes said to be the basis for the character Bluebeard in Charles Perault's 17th century fairy tale of the same name. In the fairy tale, a young woman ends up married to the mysterious Bluebeard and must enlist help from her siblings once she discovers the bloody chamber where he brutally murders all his wives. It is not clear whether or not it is true that Gilles de Rais inspired the character. There are many other candidates who may have inspired Perault. Nonetheless, Shaw is clearly drawing on the association by describing the character's dyed-blue beard.
Shaw insists that there are no villains in his play, and he sets out to portray Joan and her executioners as flawed humans. This allusion to Gilles de Rais, and the emphasis on his violent tendencies, helps highlight the complex humanity at the center of Joan's story. Joan is a saint, yes, but she also worked with a man who committed many atrocities against children. No one in this story is a paragon of morality, and even a convicted serial killer can associate with saints.
The Epilogue opens on the scene of King Charles VII reading in bed. His reading material, which Shaw specifies in the stage directions, is an allusion worth noting:
Charles is not asleep: he is reading in bed, or rather looking at the pictures in Fouquet’s Boccaccio with his knees doubled up to make a reading-desk. Beside the bed on his left is a little table with a picture of the Virgin, lighted by candles of painted wax. The walls are hung from ceiling to floor with painted curtains which stir at times in the draughts. At first glance the prevailing yellow and red in these hanging pictures is somewhat flamelike when the folds breathe in the wind.
Boccaccio is a 14th-century Italian author best known for writing the Decameron, a collection of 100 tales all drawn together by a frame story about a group of people sheltering from the plague. Fouquet was a 15th-century French painter and manuscript illuminator, or illustrator. Shaw is likely referring not to the Decameron, but rather to Fouquet's illumination of two other Boccaccio manuscripts that had been translated into French: On the Fates of Famous Men and Of Famous Women. In these books, Boccaccio collected biographies of many famous people, focusing on their glorification and, in many cases, their downfall. Fouquet's illustrated versions came out a bit after the events of the epilogue take place, but Shaw is playing with history anyway and doesn't seem to mind a bit of anachronism—for instance, a man from the 20th century appears later in Charles's dream. The frontispiece of Fouquet's manuscript is in fact a painting of Charles VII himself presiding over a trial. The allusion allows Shaw to comment cleverly on the fates of all the famous people in the play. However much we glorify them, all of them are, ultimately, dead.