More than just a very well armoured soldier, the knight was a member of the nobility and was trained vigorously for war from the age of eight.  It was said that if a boy could not ride, hunt and fight by the age of sixteen then all he was good for was the church.  Because of his good armour and extensive training it was unusual for a knight to be killed in battle, also due to his social standing and wealth the knight would usually be taken prisoner and then ransomed as opposed to just being killed.  The knight would be ransomed separately from his arms and armour, the costs of these ransoms ruined many lesser families, however with luck in the next battle a knight could regain all of his lost monies.  In the great battles in the fifteenth centaury so many French knights were captured by the English that paying the ransoms nearly destroyed the French national economy and some knights out stripped the king in income due to their success at taking prisoners. 

As time progressed so did the knights armour.  From the knights at Hastings who wore hauberks that covered most of their body from elbow to knee the later knights were literally covered in mail and with a full faced helmet there was now no part of their body that was not protected besides the eyes.  Heraldry soon started to appear in the late twelfth century, initially with the painting of patterns and devices on knights shields and then later on with the introduction of surcoats.  The surcoat was a garment that was brought back from the Crusades, a lose fitting robe worn over the armour to keep it clean and to help reflect the heat of the desert sun.  The patterns on the surcoats and shields were critical in telling the different knights apart during the heat of the battle, before their use there were accounts of knights cutting down their own brothers during the heat of battle as there was little to tell to fully armoured men apart.