The knight of 1300 was well-armored. Plate mail was still in the future, but armor had developed to the point where most of a knight was covered in metal, and even his horse wore padded armor. The knight was adept at the use of the lance, the sword and the shield, and was every bit as effective on foot as he was on horseback.
What happened in the 14th century was that there emerged other forces on the field that could withstand the feudal cavalry charge and could even win battles. The most notable of these were the English longbowmen and the Swiss pikemen.