http://www.ccel.org/c/calvin/comment...htm/ix.xiv.htm
I would assume it was a pre incarnate Christ who rescued the three. Allthough neb might not have realized it so.
At the very least it is one of Gods elect angels sent to aid the elect men of his choice. It was a special display of Gods power to a wicked ruler like pharoh as well to show his mighty works amidst great oppostion and peril.
blade