Medieval Female Jousting

Feb 2017
Devon, UK
Short answer, Symbolism. Good vs Evil. More specifically, (and this is conjecture on my part) it's possibly derived from the imagery in 'The Revelation of St John' (Chap 12) where the 'woman of the apocalypse' (usually identified with/as the Virgin Mary) uses eagle's wings (represented by the eagle in arms of the figure on the left) to escape the 'dragon' (represented by the wyvern in the arms of the figure on the right).