Your cape is currently completely flat, but has a decorative lighter colour running along the whole edge.
MdNight's cape has no decorative colour, but is all blue - however it has depth because it curves at the sides (where highlighted).
Your characters arms are half the thickness of his chest. They also only reach to his waist, whereas as you should notice your own arms and fingers reach down to over the middle of your thigh. The hands also appear the length and size of the entire forearm. Check out references! MdNight does well to fix this problem in the arms, although i would personally say his legs and feet are a bit small.