With more and more tournaments and the advancements in armour design and form the knight was soon able to protect his face with well armoured helmets and visors. This meant that his face was covered and so gave rise to the need for identifying symbols. This became part of the Heraldry system.
With knights encased in armour, it was clear that symbols on the armour would be both useful to their enemies and their allies. The armour and the need to identify the wearer were therefore directly involved with how heraldry evolved.
It is therefore important to see that heraldry was very much an individual identifier from it's early days but evolved to give that persons family symbolism and identity.