Even if you don't know your steel but know it is some type of high carbon (ie. springs, files, etc), you can get some degree of hardening by heating to non-magnetic and quench in any veggie or mineral oil.
You will know if it is hard because a file will skate across the steel rather than cut into it. Now throw it in the oven around 400 degrees for a couple of hours. If you can now cut it with a file you should be good to go. If the file still skates, back in the oven and increase the temperature til it is easy to cut with the file.
Try a little torture test by shooting it through a pine board. If tip doesn't roll over and the edge is intact, you are go to go. Most early trade points weren't even tempered.
OK before anyone hops all over this advice, remember we are dealing with a broadhead that only has to be sharp for a milli second. It just needs to hard enough so the tip doesn't fold over like a tin can lid and soft enough to sharpen easily...Team Tippit Broadheads