I would do automated natural woven shades for the two square Windows and leave upper arch open..add side panels from rod between the two square Windows hung just below the top window..I would do a large wood rod to amp up the look..with wide panels to soften the wall.

excuse my rough rendering..lol

I think shutters would be nice since they can be custom fit to the space.

These are not windows well suited to curtains, and certainly not curtains visually dividing upper and lower window. An automated woven shade, or a Sihouette shade on a remote control probably the best options. A visit from a window shade source in your area might be best road to take

Woven wood shades or honey comb shades would suit this well. Both products can be manufactured with motorized features. All you have to do is point the controller (wand) at the window and press the correct button to raise or lower the window treatment.

I disagree that drapes are not a choice...this wall needs some softness added..yes it is an unusual window placement but under the first square window you could add some wood trim work to give it some architectural feature....add rod and drapes..no need to hang drapes from first window just below is fine...I know most clients have a hard time fitting custom drapes into the budget..so this allows you to buy ready mades instead....the remote blinds are not cheap but in your case necessary! this still will make it a pretty addition to the space..sometimes you just gotta break the rules.