Quote Originally Posted by Crossblades
Are you playing the PS version of FF IV? If you are, then they changed Crystal Sword into the Ragnarok
Its name is the Ragnarok.

But yes, to the left of the entrance to B5 of the Moon's Core, is this little thin strip of land, go across an invisible bridge to go through another passage that leaves to a save point, which you should promptly save at, for you'll have to fight Dark Bahamut.