The British firm Thor make a huge variety of hammers and mallets, including brass ones in many sizes.
Although I have, and have used, brass hammers, I find that for most applications copper is preferable. I generally use the type with the iron head and replaceable faces. They have a pleasing balance and are available in a huge range of sizes, up to sledgehammer size.
Many of the Thor hammers are rebranded and distributed in the U.S. by Vaughan.
Doh! Just spotted this thread’s returned from the grave!