I don't know the origin of Lael, but the Laelia theory looks very good. Personally, I prefer Laelia to Lael. Unfortunately, Laelia's ultimate meaning is unknown.Miranda
I once heard about an angel called Lael, but I don't know if the name does excist in the Bible or other ancient / religious scriptures.. But it sounds logical if you look at the -el (Gabriel, Michael), and the meaning "of God".