Distressed is pretty easy, you just need some random, but while paying attention to wear areas. Like around a handle, or other areas where a functioning piece actually gets touched when in use.

then beat the snot out of it randomly, and with a variety of different tools, so the marks are different. Both heavy and light contacts. I've seen several pieces that were shot to inflict wounds. Shotgun blasts at 30 yards with about 6 shot can look pretty wild. 

Paint and finishes in layers, and sanded at contact spots to reveal other colors below.

Once you start doing it, other thoughts will come to you, it's the opposite of a nice finish, and if you dislike finishing, it's oddly soothing. :-)