Years ago I visited the workshop of a guy who did furniture restoration. Amidst the expected shop tools I spotted something unusual: A box filled with coins, rocks and a chain. He explained that these were his "weathering tools," for when a new piece of wood had to be integrated into an older piece. He'd judiciously drop different combinations of coins, rocks and the chain onto the wood, abrading the surface to make its wear-and-tear match the look of its neighboring panels.
I'm sure he had tricks for making hardware look antique, too, but I didn't get to see those techniques. Here, however, is a video from furniture restorer Kim Buckminster showing how he antique-ifies hardware using nothing more than a rag, acrylic paint and some fixatives for durability: