I know that mog is old content, but some people are still farming weapons so heres a lazy way to do it:

http://www.youtube.com/watch?v=-d_RKPMks6w

Strategy:
6 WHM , 1 BLM , 1 PLD

At Memento, have blissful,shroud,presence and cleric stance ready. BLM starts casting Flare when the king is charging up.
After Memento, use Stonera then a double Holy. Speed is key, otherwise they run away.