Welcome to planDisney, Redon! I am so pleased you entrusted us with your Disneyland Resort question as you continue to make plans for your upcoming visit.
A birthday trip to The Happiest Place on Earth? There truly is nothing better! Your family is going to make some very special memories that will last a lifetime and I'm so excited for all the magic awaiting you!
The Sword in the Stone is one of my favorite classic Disney films too, Redon! But, I'm afraid that Merlin the Wizard keeps all the secrets locked away about the legendary origins of Excalibur. Although we do know that whosoever can remove the sword from its anvil is indeed a true and rightful Royal! Arthur himself showed us that inner strength, intellect, and character are what is required to lift the sword, but I have a few more suggestions for you to make your son's experience all the more magical during your next visit.
First, I suggest you visit one of the Guest Relations locations throughout the theme parks or hotels of the Disneyland Resort to ask for a complimentary celebration button. It's a really special way to announce your son's birthday to fellow Guests and Cast Members who will be glad to share their happy birthday wishes, or perhaps an act of unexpected magic!
Secondly, this makes a wonderful photo memory. In fact, Disney PhotoPass photographers are often available at this location right in front of King Arthur Carrousel, along with other Picture Spots around the theme parks. With a little Higitus Figitus, I bet you'll be able to capture the perfect snapshot of your son as a worthy ruler among all of Fantasyland!
Finally, I have to share that one of my absolute favorite sights throughout the Disneyland Resort is Merlin himself, atop the Sword in the Stone float in the 'Magic Happens' parade! If you haven't had a chance to see this spectacular parade yet, I promise you it is worth the wait! Merlin's lovable eccentricities are always a highlight for me and my whole family.
Redon, I hope this is a helpful start and if we can offer any other recommendations, please come back, and share another question with us. Most of all, I hope your son knows that no matter the outcome of his efforts with Excalibur, the kindness of one's heart is the greatest show of strength. After all, "That's What Makes the World Go Round!"
Wishing you Wondrous Journeys,
Tishra