Caster doesn’t use a sword in combat and that’s a big mistake as far as I am concerned. Sasuke is an exceptionally skilled shinobi and even he realizes that using a sword will help a lot in a fight. Caster has several spells at the ready, but Sasuke will be able to speedblitz him all day. One glance from his Sharingan should also be enough to blow Caster away with Amaterasu. In short…this is an easy win for the Uchiha. Sasuke wins.