There are plenty of options. The first question is whether you want that window to be uncovered at times. If you don't the options are numerous. You could get frost film and put it in the upper window. You could get a thin, arched curtain rod that would be mounted on the trim and only cover the upper window. You could get a board --- insulating styrofoam is good, cut it to the right size and cover it with fabric, you could even paint the fabric to match the wall. If it's tight enough, it will stay in place. You can put it up in the summer and take it down in the winter. You could get a fan shade. Something like this in wood or fabric.

PLANTATION SHUTTERS - WOOD ARCH WINDOW SHUTTERS - Lafayette Woodland Harvest · More Info

IMO you get a custom solar shade made for the arch then get either 3 separate soloar shades for the 3 windows or mount a rod under the arched window and do the soalr shde extra wide . Drpes keep out the light but do not allow you to keep the view , solar shades allow the view , control the heat and the UV and cost a lot less than drapes . IMO if you do 3 solar shades and the fixed one in the arch then for nightime privacy if needed you can have nice drapes to close across thos window with one support in the cnter and the rod placed as I mentioned

I would not put a bracket on the trim. Let the window trim be a feature, don't hide it.

there are other options.

Film on the upper arch window and inside mount blinds or shades on the lowers for light control and privacy. Films can easily be removed when you change your mind. Available online and at home improvement centers for DIY easy application, or call a local installer that does commercial applications.

I would place the rod below the eyebrow arch.