I think you folks are working too hard for spear heads to use in free play. First, narrow, thin blades will simply fold over, and won't give an indicator of positive force. Moreover, most of the spear combat indicated in the FechtbÃ¼cher was Kampffechten, and it was common to fight such bouts with the visor up or off for better visibility. To simulate that you need to have a grilled visor of some sort to protect your face while still allowing proper vision, and, unless you're using perf plate, most such grills will allow a slender point to pass through, potentially causing great damage. So spear-head shaped simulators may look cool, but they actually limit the accuracy of your bouts because they limit either your targeting (i.e., you can't aim for delicate spots) or they force you to fight with a closed face, which is accurate, but probably not typical, and they do not hold up when heavy force is used.
You can achieve far better and far cheaper results with nothing more than a backpacking pad and some strapping tape (the kind with multiple fibers running through it). You will need to cut a disk of the pad which matches the diameter of your shaft, and two strips as wide as the diameter of your shaft and about 8 inches long. First, secure the disk to the end of your spear shaft with a single strip of tape that goes up and over the disk. Do not pull down hard on the tape because you don't want to compress the foam, you just want to hold it in place. Next, lay one of the strips up and over the disk you've just taped down. Make sure it is roughly even (i.e., that the ends extend down the shaft about the same distance on each side) and use two small pieces of tape to hold it in place, but don't wrap the tape around the shaft of the spear. Next, run the remaining strip of foam up and over the spear head at right angles to the previous piece and tape it in place. Now trim the ends of the two strips so the ends are all the same length. Now use the strapping tape to wrap around and around the foam, from below the foam on the bare shaft, all the way up to the tip. Runs some strips up and over the tip to completely cover it (picture an asterisk pattern) and then add more wraps around the shaft and up the foam to hold the strips that went up and over in place. The wraps of tape should be *very* tight down at the ends of the foam and looser near the very point: Be careful not to compress the tip of the foam because you want it to give when you hit someone. If you like, you can cover the entire spear head with duct tape to give it a more metallic look.
This will not give you anything that truly looks like a spear head, but it will give you a head that can be used safely for the most energetic free play (assuming safe, comprehensive armor, of course).
For pollaxe heads, the rubber axe heads (mistakenly called â€œpole hammerâ€ heads) sold by Purpleheart: http://www.woodenswords.com/WMA/pole_hammer.htm
are far superior to anything else Iâ€™ve seen or used in more than 20 years of full-contact armored pollaxe bouts (with the exception of the Rathbone-brand axe heads, but they no longer make the ones that simulate a pollaxe well). Simply slide these onto a shaft far enough down that the shaft above the axe head simulates a dague, then make another padded point as described above for the spear head. This is the only pollaxe construction method approved for use in my Schule.