At the level of minimal effort/cost, I think a thicker mantle, and plaster (stucco, render) the brick above the mantel and paint the same colour as the wall. You might paint the bronze black -- or rather, near-black. Check out your local paint store for advice on what to use for that and how to do it. If you have a bigger budget, the sky's the limit with what can be done to a fireplace, but for Houzzers to suggest what might work best with your room would probably require a couple of pics of the rest of the room to get the general style. Good luck!