LOL I have to laugh because on this page is an advertisement for steel pointed hammers. However, they are expensive! The helmet I once wore was the only armor I carried and during rocket or mortar attacks, I could get most of my body under it except for my left knee. :) But they were never that strong as they were only strong enough to stop small shrapnel and were dented easily. The kinetic energy of a 25mm steel ball from one of your powerful sling-shots would have been enough to dent it considerably and give the wearer a headache.
Whats going on with the subtitles? They are really bad. Nice video otherwise