Storm Brand

The Storm Brand is a Long Sword-class Artifact weapon available in  and Golden Sun: Dark Dawn.

In
In The Lost Age, it is found in a treasure chest "early" in the massive Air's Rock dungeon — technically in the first screen with the sand maze, in fact. However, the sand maze will take a while to pass with the Whirlwind Psynergy, and you will have to have opened up the route to the chest in the screen's northwest corner before climbing up the first cliff screen at its west end and then climbing back down toward the chest at its east end.

The Storm Brand's Unleash effect is Hurricane, which is a Mercury-aligned physical attack with 21 points of damage added and a 60% base chance to reduce the target's Attack stat by two 12.5% "stages" for several turns (down to a maximum of four stages totaling -50%). Hurricane visually resembles a narrow torrent of rain drops hitting the target at a slight angle before the wielder attacks them physically.

The Storm Brand is a textbook example of a weapon artifact in The Lost Age that is found effectively for "free" in a chest in one of the game's prominent dungeon-style locations, and it is clearly stronger than anything the party is expected to hold by that point. Even though Felix, the only Adept capable of wielding it at this point, is a Venus Adept who cannot easily capitalize on the Unleash's Mercury alignment, the damage output and attack-stat decreases of its Unleashes can make this useful in the Briggs boss battle and far beyond.

It will be succeeded by the stronger Disk Axe not too long afterward in Kibombo Mountains, but keep the Storm Brand in your inventory until you recruit Piers at Kibombo shortly after so that his generic Battle Mace can be immediately replaced with the superior Storm Brand as a hand-me-down. It is possible for the Storm Brand to remain in Piers' hands until a fair time has passed in the Eastern Sea segment of the game, where it can be replaced by crafted/reforged gear like Captain's Axe and Comet Mace even before the significantly stronger Mist Sabre is picked up in Aqua Rock.

The Storm Brand can technically be held by Isaac and Garet very late in the game, though the fact it is functionally identical to the first game's midgame-level Arctic Blade (save for a few extra points in Attack increase and Unleash damage) means there is little appeal in having them attack with this.

In
In Dark Dawn, the Storm Brand is found in a treasure chest in Barai Temple, and can be equipped by Matthew and Tyrell. The Storm Brand retains Hurricane as its signature Unleash, but it also gains a secondary Unleash learned beforehand, the basic Critical Strike. This is simply a non-elemental physical attack that deals 50% more damage, which can be seen as a downside because the redesigned Unleash system makes this weapon randomly choose between this and the potentially more useful and utility-filled Hurricane.

Regardless, the Storm Brand is the strongest weapon available to the player at the time it is found. However, in order to Unleash Hurricane at its highest power, Matthew and Tyrell must have Mercury Djinn set to them, as there is no Mercury Adept in your party capable of equipping the Storm Brand. Since Tyrell can later acquire the Vulcan Axe, which has a Mars-based Unleash, the player may consider equipping the Storm Brand to Matthew.

Gallery of Dark Dawn unleashes