Simplify the following text for a Grade 4 native English-speaking person.
Original: However , in what is sometimes called the Post-Vulgate Merlin , Excalibur was given to Arthur by the Lady of the Lake sometime after he began to reign .
Simplified: The second Excalibur was the one to which Merlin took the King . The sword was located at a magical lake where the Lady of the Lake gave it to Arthur .