Yes, Chase and Oliver had the same teacher, but Oliver has had years of fighting bad guys under his belt, including Ras Al Ghul and Slade Wilson, so you'd think he might be a bit tougher than Chase.

I know it's all a morality play, but it's ridiculous to have the heroes go on and on about how killing Chase will be something that will turn your soul dark and you'll never recover from, only to have scenes of Diggle, Black Canary and especially Wild Dog shoot their way through scores of henchmen!