Capes are usually made with a constant radius from the neck, this isn’t. This seems more like an ellipse. Either the sides are shorter or the back is longer.
Hard edge? It’s just folded out of the way emphasizing the difference in length.
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Capes can be any amount of a circle, Battinson looks like most of a full circle, where when the ‘sides’ are draped down in front of him instead of folded over his shoulder the bottom of the cape is uniform length.
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Edit:
In which case, the radius of the cape could be uniform, but with the neck off centre, like this drawing I just did.
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