IIRC, its generally been house rules, but in the games I've played you could always declare that you were trying not to injure them, using the pommel, flat of the blade, butt of spear, etc. The "damage" was then opposed by CON (don't remember the multiple but I think it was x1) on the Resistance table. The results of a successful roll would vary depending upon location hit; arms, weapon dropped, head, KO, etc. Armor did count.
SDLeary