Masamune

The Masamune is a Light Blade found in Golden Sun: The Lost Age. It is found in a treasure chest in Yallam, but the Force Psynergy is required to reach the chest, meaning the Masamune will be unavailable until after Jupiter Lighthouse. It can be bought for 16400 coins and sold for 12300 coins. Being a Light Blade, it can be equipped by Isaac, Felix, Garet, Jenna, Ivan, and Piers. It increases the wielder's attack by 161.

The Masamune's Unleash attack is Rising Dragon, which activates at a rate of 40% (notable, since most Unleashes activate at a rate of 35%). Rising Dragon converts all damage to Mercury damage and attacks with an additional 62 damage points. Also, there is a chance of doing twice the normal amount of damage. Visually, Rising Dragon resembles a light blue cloud with the shape of a dragon's head at the front streaming from the attacker and arcing slightly before striking the target from above. If Rising Dragon does double damage, a second, identical cloud follows, only this cloud strikes from below.

The Masamune is a powerful weapon that can be acquired easily and be equipped to almost anyone. However, it remains unavailable until late into the game, meaning it merely serves as a placeholder for more powerful weapons like Tisiphone Edge and Excalibur, both of which are capable of attacking for three times their normal damage. However, in terms of raw power, no weapon can outdo a two-strike Rising Dragon from the Masamune until the above mentioned weapons or the Sol Blade are acquired. Even then, it is worth considering that Masamune does water damage, not earth or wind.

The Masamune is the most powerful Mercury based weapon Piers can equip in the game. Although it's a Light Blade both it's base attack and bonus Mercury damage from it's unleash are higher than it's nearest contender the Mythril Blade. On top of this the Masamune has a chance to do double damage, pushing it well in front of the Mythril Blade, however it is still inferior to several weapons of different elements available at the end of the game such as the Tisiphone Edge and Excalibur. Considering it is the most powerful Mercury based weapon Piers can equip, if you keep Piers in one of his Mercury based classes the Masamune is a solid end game choice for him.

In the original Golden Sun, a weapon hidden in the game's code named "Masamune" can be seen and found either through hacking or in the Debug Rooms. It is a Light Blade with a unique and different graphic not officially seen in either game, has 135 Atk, and has no Unleash effect. If transferred into The Lost Age, it becomes the Fire Brand.

Cultural references
Okazaki Masamune, who lived in the 13th and 14th centuries, is regarded as the greatest swordsmith of Japanese history. In addition to his extraordinary worksmanship, he is typically regarded as the exemplar of the true warrior who does not kill needlessly, in contrast to Muramasa's alleged bloodthirst.