Take some mild steel rod, maybe 1/4 inch diameter by 8 inches long, hammer a flat on one end and use a cold chisel to cut to a spear point. Bend the first 1/2 inch of the other end so the rod is now an "L" shape. Drill a socket for this in the side of your improvised spear handle and insert the "L" into the hole before lashing. Three of these and you're good to go. A lighter tine could be made from brazing rod.