I agree the edges are too sharp. I tried a blur just over the edge Using a soft brush . It takes the edge off no pun intended . It doesn't seem to adversely affect the shape.
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A field of depth blur might also help the Illusion of height. I am not sure what you mean by the last part of your post ?
Also trying to figure out a way to convey the sharper angle/slope of the building from the base to the pyramid (as compared to the angle/slope of the pyramid topper).