Soften the brass first before trying to bend it.
I soften brass by heating it hot and allowing it to cool in air but others will probably say dunk in water. The reality is that I don't believe that it matters provided that it is heated hot. I say heat to hot and not red because with something like a brass belt hanger it will be very easy to melt. The difference between heat treated, softened, brass and brass that has not been softened by heat treatment will be very noticeable.
When I needed a brass belt hanger, some years ago for a bayonet scabbard I made my own from a piece of brass rod, copying an original for size.