Vulcan Axe

The Vulcan Axe (Smog Axe in Japan) is an axe found in Golden Sun and Golden Sun: Dark Dawn. In Golden Sun, it is found in a hidden chest early on in Lamakan Desert that can only be seen (and opened) if Reveal is used near it, and the chest is located in an area that otherwise appears to be a dead-end. In Dark Dawn, it can be found in a chest in The Ouroboros labyrinth. Being an axe, it can be equipped by Isaac, Felix, Garet, Piers, Matthew, Tyrell and Eoleo. It can be bought for 4600 coins and sold for 3450 coins.

In Golden Sun
The Vulcan Axe increases the wielder's base Attack rating by 76, and is noteworthy for being a weapon whose normal attack is an elemental physical attack like its Unleash effect, with the element being Mars (in other words, after striking an enemy with a normal attack with this weapon, the game either increases or decreases the damage done based on whether the user's Mars power is higher or lower than the target's Mars resistance). Its Mars-based Unleash effect, activating at the standard base rate of 35% of the time, is Barrage (Explosion in Japan), which adds 20 points of damage to the attack's result and attempts to stun the target. Barrage appears as the axe strike creating an intense explosion of flame with a few sparks being emitted.

Analysis
The Vulcan Axe, as is typical of many weapon artifacts, is easily the best weapon the party has when it can first be  collected. It is one of a scant few weapons in either game whose normal attacks convert to an element, which means its damage is easily affected  by enemy resistances. Watery monsters, or more precisely any monster with a low Mars resistance rating, will always receive enhanced damage  from this axe whether it Unleashes or not, making it a great weapon to  use in the boss fight with the Kraken a little later on, and its  damage increases if its wielder has a higher Mars power rating. Garet is typically a strong candidate for holding the axe, but so is Isaac if  two Mars-based attackers is better in a particular battle, and  particularly if Isaac has Mars Djinn set onto him to make his class of  the Brute class series.

In Dark Dawn
The Vulcan Axe raises the wielder's attack by 76 and converts all normal damage to Mars damage. It gains one new unleash, Critical Strike. Critical Strike, normally a non-elemental unleash, is converted to a Mars-affiliated unleash due to the Vulcan Axe's pure-element nature, and multiplies damage by 1.5. Barrage remains the main Unleash, and maintains its mechanics from the first game.

Analysis
The Vulcan Axe is a great weapon for Tyrell to wield, due to his naturally high Mars Power. However, Matthew can also make use of the weapon if he given set Mars Djinn to make his class the Brute class series. The Vulcan Axe is an extremely useful weapon to have on hand for the boss battle against the Ice Queen in Harapa Ruins, due to her low Mars Resistance.

Cultural References
Vulcan, also known as Hephaestus in Greek, was the Roman god of technology, blacksmiths, craftsmen, artisans, sculptors, metals, metallurgy, fire and volcanoes.