Take that 10 pounder outside, and use it till the handle breaks. Then get a peice of round stock (solid steel bar) Weld the round stock to the hammer head. I have a 35 pound sledge from doing that. I am sure it changes the swing dynamics a little, but I haven't broke a handle splitting wood in a long time.
If you don't have a welder or don't know how to weld, ask one of your friends to do it. Look for someone wearing cowboy boots, they can weld the best.