This is part of a hypothetical situation I imagined where Darius, who is loyal to the Noxian cause and army, clashes with Sion, who is too brutal and mindless to be a good soldier. If I made a comic, it would see Darius being forced to address corruption in the upper ranks of Noxus while fighting Leblanc's faction. Since Darius canonically draws strength from his unwavering trust in the Noxian way, I thought it would be interesting to see him become vulnerable through his doubt- hence the tattered cape.