The Catching of The Sword.
In a monarchy when a prince is ready to succeed his father as king he not only needs to proove himself to his family but the rest of the people that he shall be the ruler of, by a symbolic action. Most of the time it's done on the battlefield along side his men. In the book "The Hollow Hills" by Mary Stewart this action is shown by "Emrys" with the catching of his father's sword on the battle field.
"Emrys" did not know that the king was his father and niether did anyone else besides the King, Merlin, and Ralf. Which in turn, caused the scene to be worth even more in the eyes of the people watching and most importantly the King's. There, white, on white horse, the King's fighting spirit had leaped, it seemed, out of his failing body, and run ahead, like the spark on the top of a fighting spear, straight to the heart of the Saxon force.
This simile describes the overwhelming feeling of the King watching his son, who he had not seen since birth, follow in his footsteps. It's something special to a father watching there son succeed themselves. The king was as close to death as could be and his son not even knowing who he really was or what, for that matter of fact, saved him by his own sword. This action also motivated the rest of the troops. But the day was already won. There was no man there on the field who had not seen what had happened. The troops saw it as a sign from the heavens above and knew that a God was on their side that day, which ever one it was, seeing that Merlin foretold right, as he always had in the past.
This scene not only shows the importance of "Emrys", also known as Arthur, in the story but also the importance that Merlin held in Arthur's heart. Arthur felt that Merlin was a God watching over him from his post at rock. It made him feel as if nothing bad could happen to him. This moment changed life for young Arthur. Everything moved so fast, and yet so slowly and clearly, every moment seemed to last forever. I never knew one could be blazing hot and ice-cold all at the same moment, did you? This is the point in Arthur's life when he changes from the young boy he was, galloping through the forest to visit Merlin, to the king he will become beckoning Merlin towards him for help. Merlin will always be the closest at heart to Athur. They share a bond through the heart and it will never be broken. It's as if even though they are miles apart, they are truly right next to eachother. Which is foreshadowing to the future with Merlin at Arthur's side as he takes the role of King of Great Britain.
That is how the action of Arthur catching the sword symbolizes what is in store for Great Britain. It showed them that Arthur would make a great leader and a great soldier.