I really like the classical style in which you have written this duel, with the comparisons to Roman gods, their symbols, and above all, the use of their magic in their own colours. It seems very appropriate for the duel that signified the beginning of a new wizarding age, one of universal magical education. The duel itself is the mythology and central guiding principle for many a Gryffindor and Slytherin who later passed through the school halls.
As to the duel itself - I enjoyed getting a proper sword fight. I admire the way you worked magic with, through and around the swords. Magical weapons were probably quite necessary for a community who had to defend themselves against any locals and knights who sought to stamp out witchcraft. I also like that you inferred that neither Slytherin nor Gryffindor passed their skills onto another, another symbol of the ending of an age.