In our humble opinion, a plantation shutter with a fully louvered custom manufactured arch is the best option. While there are many other options for covering these types of windows, none provide the clean seamless control of a fully louvered arch shutter.
The diagram below shows the basic dimensions of how to visualize the look in your window. We know of no other option that is durable and affordable while allowing for adjustable light control. It really is the "Cadillac" window covering application for your arch shaped window.