Excalibur

An Excalibur is an Artifact Long Sword-class weapon available in Golden Sun: The Lost Age and Golden Sun: Dark Dawn. It is forged from an Orihalcon, and it has one of the highest base attack ratings of any weapon in the series and one of the most potentially powerful Unleashes as well.

Basic description by game
The Excalibur increases its wielder's base Attack by 180 points, which is the highest attack rating increase of any piece of any non-Cursed and non-unique equipment in The Lost Age - only the the unique Sol Blade, with 200 attack, and the Cursed Darksword, with 210 attack, has higher base attack raitings. It is an Artifact weapon that is only acquired by bringing an Orihalcon forgeable material to the  blacksmith in Yallam so that it may be turned either  this or one of several other items chosen at random, with the chance of the Excalibur being forged being a rare 5%, and you must pay  its 29200 buy value in order to obtain it. Afterward, it can be sold for 21900 coins, and can subsequently be bought back for 21900 coins. As a Long Sword, this can be equipped by Felix, Piers, Isaac, and Garet.

Its Unleash effect, Legend, deals a Jupiter-aligned attack equal to the  user's normal physical attack with 73 damage points added to the  results, and there is a 60% chance that it will multiply the resultant damage by 3. Therefore, it can be said that this Unleash has an average damage multiplier pf 2.2. Visually, Legend resembles a three-dimensional purple light hologram of a symbol form above the enemy party, and the symbol generates either one holographic sword that drives  itself into the target or three holographic swords that drive  themselves into the target in succession, depending on whether Legend tripled the damage or not.

In Dark Dawn, the Excalibur is obtained in much the same way, where you must bring an Orihalcon to Obaba at Champa and hope she forges it into this, though like all other equipment she forges she will give it to you for  free. It and its Legend unleash have all the same statistics, and is equippable only by Matthew and Tyrell. With the different Unleash mechanics, Legend is now the fourth and final Unleash that the wielder may gain the ability to randomly choose from whenever he unleashes. Its first Unleash is Critical Move, which is simply a physical attack with the resultant damage multiplied by 1.4. Its second Unleash is Rolling Attack, which is a Jupiter-aligned attack equal to the user's normal physical  attack with the result multiplied by 1.1, and hits each adjacent foe so  that up to three foes may be hit; and its third Unleash is Sky  Diver, which is a Jupiter-aligned attack equal to the user's normal  physical attack with 66 added damage and the chance to inflict the  Stun status condition.

The Lost Age
In The Lost Age, the Excalibur is one of the game's best weapons and is often identified as on of the game's "ultimate" weapons, by virtue of being the closest weapon to the Sol Blade in power and usability. The one Sol Blade that the party is allowed to have has 20 more base Attack, and its Megiddo Unleash has the enormous effect of automatically tripling all damage done, always. But for the other three Long Sword-wielding warriors in your party that aren't equipped with it, the Excalibur is still the best weapon for them to hold, being slightly better than even the Tisiphone Edge because that has a little less Attack and a little less chance to score triple damage with its own Unleash. Unlike the Sol Blade it is possible to get multiple copies, and because of its power, having multiple Excaliburs will not go to waste in any game. It is an ideal weapon to bring to the final boss and any of the optional bosses - Valukar, Sentinel, Star Magician, and Dullahan.

As a weapon to Unleash with, the Excalibur is basically a more randomized form of Sol Blade's Megiddo that is generally weaker on average, but has the potential to score even higher bursts of damage if luck happens for the player - and this luck has a 60% chance to trigger each time Legend is unleashed. When Legend ends up tripling its resultant damage, the 73 bonus damage at the core of the Unleash gets tripled along with the normal damage of the attack, to 219 bonus damage, which essentially guarantees a higher damage result on a target than the same user unleashing Megiddo on the same target. Like with the Sol Blade, the Excalibur's usefulness can be enormously improved by wearing lots of gear that increases its Unleash rate, like the Valkyrie Mail or Mythril Clothes on the body, the Mythril Helm or Warrior's Helm on the Riot Gloves or Aegis Shield on the arms, and the Hyper Boots.

That Legend's elemental affinity is Jupiter is a minor downside because there are no Long Sword-wielding Jupiter Adepts whose Jupiter power ratings can work in tandem with the Unleash. The ideal user of Excalibur is an Adept in the Master class, which is just like the excellent Chaos Lord class in having the highest attack rating in the game, but it also has five Jupiter Djinn Set to grant the wielder 25 additional Jupiter power. When it comes to equipment that can also increase the warrior Adept's Jupiter power, the only possibilities that exist are the Aerial Gloves and Planet Armor, and one would not want to wear these in place of the gloves and armor that increase Unleash rate, like the Mythril Clothes and Aegis Shield noted above.

Dark Dawn
In Dark Dawn, Matthew and Tyrell are now the only two Long Sword users in the game, and since Matthew would be holding the game's best weapon, the Sol Blade, which only he can equip to begin with, the only character who would use the weapon is Tyrell. As a result, one Excalibur at most can be useful for an end-game party. Like before, the Master and Chaos Lord classes are the best classes for either Matthew or Tyrell to be using Excalibur with because of the top-notch attack ratings they provide and the additional Jupiter power increase the Master class provides.

While still a useful weapon if it can be acquired, the Excalibur has weakened substantially from The Lost Age due to the redesigned Unleash system, which adds several additional weaker Unleashes to it that the game randomly chooses from each time the user makes an Unleash with the weapon. The other "ultimate" weapons become less consistently powerful for the same reasons, but the Excalibur is particularly downgraded in usability because it now has three other unleashes that are all weaker than even the single-strike form of Legend. The first Unleash that the wielder may learn to trigger, Critical Strike, is only a physical attack with a damage multiplier of x1.4 - to put the weakness of this Unleash in perspective, the Sol Blade's new first Unleash, Centurion, has a damage multiplier of x2.4 and may ignore half of the target's defense, and many basic weapons have a non-elemental Unleash that has a x1.5 multiplier.

The second Unleash, Rolling Attack, is a Jupiter-aligned attack equal to the user's physical attack with a x1.1 multiplier, and each adjacent foe is also hit, so that this attack hits up to three enemies at once. This can have some usefulness in random battles, but it should be noted that even the Darksword has a multi-target unleash with a higher damage multiplier (x1.3). Its third Unleash, Sky Diver, is another Jupiter-aligned Unleash, and while it adds a pretty good 66 damage and may inflict the pretty useful Stun status condition, Legend is of course far superior because it adds even more base bonus damage and has the chance to triple the total damage done. Since all three of the Excalibur's elementally-aligned Unleashes are aligned with Jupiter, the increased Jupiter Power of the Master class does become a bonus that's all the more relevant. But unfortunately, with Legend now being one out of four randomly chosen Unleash effects, on top of it only having the chance to trigger its damage-tripling effect when it is Unleashed, scoring that enormous burst of damage with an Excalibur unleash is now rather uncommon.

As a result, the Excalibur can no longer be considered the penultimate Long Sword after the Sol Blade, and it can be stated that it is now completely outclassed by the Levatine when considered as a weapon for Tyrell to use. While the Levatine's first unleash is the same weak Critical Move that the Excalibur has, it has only two other unleashes, and both of them are useful in their own ways. One of them is the powerful and reliable Centurion, which is Jupiter-aligned and has a high-enough multiplier that it would end up doing more damage than Legend on average. The other Unleash is the Mars-aligned multi-target Radiant Fire, which adds a good damage bonus and is increased by Tyrell's high Mars power rating. This means that the Levatine is much more likely to trigger a strong attack when it Unleashes. Assuming that each of a weapon's Unleashes has an equal chance of occurring when an Unleash with that weapon is triggered, the average damage multiplier from an Unleash from the Excalibur would be x1.425, whereas the average damage multiplier from an Unleash from the Levatine would be x1.6. A damage-tripled Legend Unleash is still potentially the most powerful Unleash in the game, but on the uncommon chance it triggers, it might be wasted on most enemies.

Overall, Excalibur has fallen far from its title as an "ultimate" weapon which it originally had in The Lost Age. It would still be a good weapon to have on Tyrell if the player manages to forge it from an Orihalcon without managing to forge a Levatine from a Mythril Silver, though this scenario is unlikely because the Levatine has a higher chance of being forged from a Mythril Silver, and the Mythril Silver is a more common forgeable material as well. But on an ideal endgame party, Levatine is easily the superior choice as Tyrell's weapon, as that is his most powerful damage-multiplying weapon, even though its big damage multiplier is also Jupiter-aligned.

Cultural References
Excalibur (derived from Welsh Caledfwlch, usually understood as hard-cleft) is the sword of the mythical King Arthur. Owing to its fame, it appears in several other games.