Part of it is the wire bend, The wire used be it stainless steel, spring steel or piano depending and density of it and gage, the weight balance, the blades and shape thickness, kind of material, and weight and spacing of the blades, the umbrella skirt that helps with balance also
Piano wire, or "music wire", is a specialized type of wire made for use in piano strings. It is made from tempered high-carbon steel, also known as spring steel, which replaced iron as the material starting in 1834.