Saw it in many TV shows, that the wounded soldiers of the defeated army were finished off by stabbing them. Was it that bad? It seems reasonable, that the victorious army didn't want to share the rare medical resources with the opponent, but killing everybody unable to walk off seems a little bit harsh.
Sorry for my bad english, I am not a native speaker =)
Often they used a misericorde from the Latin 'Mercy Stroke' which was a thin bladed weapon which could slide through the armpit gaps in a knights armour to pierce the heart killing them faster.