half-swording is a technique you use at an opponent with full armor and your blade can't cut or stab through the armor gap. You grab the blade with both hands to get a better grip & for more accuracy and hit the opponent with blunt force. It is fatal but forbidden to use on a battlefield? No, on a battlefield there's so much going on and using half swording means getting closer to your opponent which is dangerous, so it's really situational, not necessarily forbidden