Brass hammers are actually not uncommon. They’re considered a “soft face” hammer where you strike other metals. They’re also considered “sparkless”, meaning they won’t throw an accidental spark. Common on oil rigs. Since brass deforms, the plates are replaceable - much like your design.
Not a fan of your approach, seems rather pointless, but who am I to judge. At first I thought you wanted to make the “in case of emergency break glass” hammer look better, since most of them are never ever used but have to be visible and accessible at all times, sorta like a better looking fire extinguisher. That would actually be a business opportunity and not just provoking art (which too has its’ place in this world)