Yeah, an HDPE wedge would likely get fairly blunt in just one fight.. However a simple way to do it may just be to make an HDPE wedge and then bolt a bit of sheet steel to the end of it to give it some strength. Something like 2mm mild steel sheet would probably work fine for non- spinner combat, as the HDPE behind it will stop it bending, and the steel on top will stop it going blunt.