Weight Spell

"I've enchanted Arthur's sword. It holds the weight of a thousand ages. No one could bear it for long."

- Morgana to Annis

Weight Spells are enchantments that add weight to an object. The spell used by Morgana was said to add the "weight of a thousand ages" to an object, making it impossible to bear for long.

History
On the eve of Arthur's duel with Derian, Morgana placed an enchantment on Arthur's sword so that it would become too heavy for him to hold. To do so, she arranged three fires into a triangle, then knelt in the center and chanted the spell. As her eyes turned gold, she held up the sword and its blade caught fire. She then incanted the second part of the spell. When the sword ceased to burn, she gave it back to Agravaine and he returned it to Arthur's tent.

The next day, during the duel between Arthur and Derian, Morgana activated the enchantment with a nonverbal spell, forcing Arthur to drop his sword. Fortunately, Merlin used his magic to protect Arthur and helped him take possession of Derian's sword so he could win the duel (His Father's Son).

Trivia

 * The enchantment on Arthur's sword remained dormant until activated with a nonverbal spell (His Father's Son).