There are a few ways to help a brick wall carry the weight of everything above a window opening. Timber, stone, concrete, steel lintel, or an arch. A steel lintel is a common choice today. It is fairly strong, easy installation and lasts 20-100 years depending on the skill of the builders, the location on the house, climate etc. It is vulnerable in fires (it quickly loses strength when heated). Maintenance/replacement is complex and expensive requiring special tools and imported materials (at least the modern ones, old-school steel is more easily available maybe) not especially environmentally friendly by skilled professionals and it involves the partial destruction of that part of the wall. A brick arch over a window is relatively simple to build. It is immensely strong and far more fire resistant. It requires no special materials, you just arrange the bricks the you were already using in a different manner. No special maintenance is required and it will last as long as the brick wall itself. The necessary materials are readily available almost anywhere and uses only renewable resources and energy in a pinch. A brick arch is also charming and easy on the eye.