The Saw bug is a bug in The Final Fantasy Legend concerning the Saw weapon and ability.
Saw is a weapon that is intended to cause Dead on the enemy if the user's strength is greater than the target's defense. For the most part, this is a useful weapon on most random encounters, but not terribly useful against bosses and certainly useless against the final boss.
However, the formula for the Saw is reversed, meaning that the Saw only works against enemies who have more defense than the player's strength. For random encounters, this weapon is useless, but sporting 200 defense, the Creator is suddenly a very viable target as long as the player hasn't raised their strength to obscene levels.