Leon is a young man with tanned skin, purple eyes, and spiked dark purple hair that is swept back. In his normal appearance, he carries a curved sword and wears dark purple armor trimmed with bronze with spiked pauldrons and bronze knee pads. He also wears leather boots and has a large red jewel on his belt. As the Emperor's Dark Knight, he wears an ornate set of black armor trimmed with gold, a helmet with curved gold horns, and a red cape.
Leon's personality before becoming the Dark Knight is unknown, but he seems to have cared for his sister Maria deeply. As the Dark Knight, he is power-hungry and authoritative, often rude and harsh to Firion and his party. His dreams end up being dashed and he comes to regret his decisions, hoping that someday he will be forgiven.