Here's another thing that helps ease the stress on your arm. Before fitting a new handle in a hammer, drill a 1/8 to 1/4 inch hole through the handle about 3 inches down the handle from where the closest part of the head will be. The hole must be through at right angles to the direction of the hammer head, ie., drilled from one side to the other. Then saw a slit from the end down to the hole. The hole is there so the saw slit won't travel (split) down the handle. Then fit he head to the handle. When properly fitted, the part of the slit inside the head will be pinched closed, and should not be used for one of the wedges. Since my aim with a saw is not too good, I find it easiest to saw almost all the way, then drill just ahead of the saw slit.

The slit somehow takes a lot of shock out of the hammer. Read about it a couple years ago, and tried it. It works for me! Slit handles and an elbow brace used every time I forge, and I haven't had the sore elbow again.

Another answer is heat. I know serveral farriers who have suffered greatly with carpel tunnel because of hammering metal too cold too often.

Willie Calhoun