We frequently recommend leaving the arch open free of any type of covering if possible. When light and privacy are not a problem, then an open window may be right for your situation. Window film can be applied to reduce the intensity and amount of light that enters through the opening. Window film can also provide privacy.
Arch top shutters can be installed, but are difficult to measure for and are quite expensive. However, they are easily the best application in terms of quality and appearance.
Arch top shutters cover the rectangular portion of a window plus the arch at the top of the window. The tops of the shutters are constructed to follow the curve of the arch.
Fan shutter tops are only the only the curved shutter. Fan top shutters usually have louvers that radiate from the center of the bottom of the shutter to the edges.
Arches can be made as part of a circle or a full half circle. Detailed measurements are critical to proper construction of an arch top or fan top shutter.