[katana]

I remember seeing a series of programmes hosted by an Ancient weapons expert, unfortunately his name escapes me. He, using very old training manuscripts, books etc. has been able to 're-create' the Martial arts of earlier periods.
The swordplay of Knights is not quite the chivalrous acts of battle the 'films' would have us believe. Every part of the sword is potentually used to strike an opponent,(even holding the tip end and striking with the cross guard.. a la 'war hammer') as are elbows, knees, feet, head and fists. The dagger was a secondary weapon often used with the technique of getting your opponent to the ground. Because, of the limitations of 'moveable' armour plate in the groin area (because of the natural range of leg movement in that area would be restricated by armour) it was a natural target area when the opponent was forced to the ground. Easier, than trying to force a dagger into the gaps in the armour elsewear.
There are two main arteries (femoral) that supply blood to the legs, this main artery was the intended target in the groin area, causing rapid blood loss.