First make sure Lloyd has the Material Blades and the Eternal Swordsman title on and Sheena in your party. Then put everyone in your party on manual. Remove anything off Lloyd that will raise his defense. Then go into the deepest part of Derris-kharlan and fight one of the angels around. let them kill you and then put Sheena on Auto and when she revives you with 0 HP put her back on manual and get one of the angels attention. When they cast a powerful spell such as Ice Tornado, Eruption ect. use falcons crest ( quickly press x, a, and b at the time, and make sure you do it before the spell kills you) and when you die you'll be laying there with the eternal sword in your hand. When i did it, it worked but it froze and i didn't get to fight with it, so make sure you save before attempting this cheat. But trust me, you can fight with it. There are YouTube videos where they fight with it, so yeah, it works.