Complex sentence: He had a beard, which was rare for Elves; but he was of great age at the time of the War of the Ring, being first mentioned around the time of Melkor's imprisonment at the begining of the first age.
Split into simpler sentences: He had a beard, which was rare for Elves, and was of great age at the time of the War of the Ring. He was first mentioned around the time of Melkor's imprisonment at the begining of the first age.