Storm Brand

The Storm Brand is a Long Sword-class weapon Artifact available in Golden Sun: The Lost Age and Golden Sun: Dark Dawn. In The Lost Age, it is found in a treasure chest in the first screen at the bottom of the massive Air's Rock dungeon. In Dark Dawn, it is found in a treasure chest in Barai Temple. Being a Long Sword-class weapon, the Storm Brand can be equipped on warrior-style Adepts, namely Felix, Piers, Isaac, Garet, Matthew, and Tyrell. It can be bought for 3900 coins and sold for 2925 coins.

In ''The Lost Age
The Storm Brand increases the wielder's base Attack rating by 60 points. Its Unleash effect is Hurricane, with the standard base activation rate of 35%, which is a physical attack with an additional 21 points of damage added, and then the resulting damage is either increased or decreased based on how the user's Mercury power measures against the target's Mercury resistance. The Unleash may also decrease the target's total Attack rating by 25% (the maximum amount any character or enemy in the game can have its Attack rating decreased or increased is up to 50% from the norm, so this side effect can successfully occur twice profitably). Visually, Hurricane resembles a torrent of rain drops hitting the target before the holder of the sword attacks them physically.

Analysis
The Storm Brand is a textbook example of a weapon artifact in The Lost Age that is found in a chest in one of the game's big  dungeon-style locations, and when it can first be found it is noticeably  strong, certainly stronger than any weapon Artifact that you can buy  from vendors at the time. It is easily the strongest weapon you can find yet for Felix during your first visit to Osenia and is useful to  use in the Briggs boss battle, in spite of the fact Felix is a Venus Adept and the weapon's Unleash effect is Mercury-based. When travelling into lower Gondowan sometime afterwards, the Storm Brand will be  outclassed by the Disk Axe you can find in Kibombo Mountains,  but it is advisable to keep it in your inventory for when the Mercury  Adept warrior Piers joins your party shortly afterward. He will be holding a Battle Mace, but the Storm Brand is an instant perfect fit  for him because it has even more Attack and Piers' Mercury power (as  well as the fact he can potentially  have four  Mercury Djinn set onto him as soon as he joins) will make the Hurricane  unleash all the more damaging. The Storm Brand can easily last a while, and can be reliably replaced by the Mist Sabre found in Aqua  Rock later on (or a Comet Mace if you manage to forge it from  Stardust at the blacksmith in Yallam).

In Dark Dawn
As in The Lost Age, the Storm Brand raises the wielder's Attack by 60 points. It now has two Unleashes: Critical Strike, a non-elemental attack that multiplies damage by 1.5, and Hurricane, which retains its characteristics from The Lost Age.

Analysis
At the time it is found, the Storm Brand is the strongest weapon available to the player. 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.