Get into a battle with Lloyd as your controlled character, have the Material Blade and Voodoo Doll equipped(or have Raine cast Revive when you get into the battle), and have 1 HP(he doesn't have to have exactly 1 HP, it just makes it easier). Run up to an enemy, and just as they are about to hit Lloyd, press A+B+X to perform Falcon's Crest. If done correctly, Lloyd will die while casting Falcon's Crest and be revived. This takes practice and patience. Lloyd will still have the Eternal Sword in his hand, and will continue to attack as though he had two swords. However, since he only has one sword, only attacks using the hand with the Eternal Sword in it will be able to do damage. Equipping different swords results in having only one of those swords, also. Video here.
Submitted by: Matt