Golden Sun: The Lost Age Tips

Lachesis' Rule
I found the most powerful staff in the game purely by accident. This is the most powerful weapon that either Sheba or Ivan can use. It's equipping effect is +177 and it unleashes Apocalypse, which calls the spirit of death onto your foes occasionaly.

First of all, to obtain this weapon you will need to have access to the Anemos Inner Sanctum by finding every single djinni. Then, you will need to wander around inside until you find a Mad Demon, doesn't matter if it is with other monsters. You have to have enough djinni in standby to summom the god Eclipse. Battle the Mad Demon but do not kill it. When ready, summon Eclipse to finish off the monster. This should produce the staff.

I am not really sure if this is how I got the weapon but this is the only thing in the battle that could contribute to its appearance. Best of luck with this. I hope I'm not wrong.