Phaeton's Blade

Phaeton's Blade is a Light Blade-class Artifact weapon found in Golden Sun: The Lost Age and Golden Sun: Dark Dawn.

Basic description by game
In all games it appears in, Phaeton's Blade increases the wielder's Attack by 151 points. It can be sold for 10200 coins, and subsequently rebought for 13600 coins.

In The Lost Age, it is found in a treasure chest in Jupiter Lighthouse, in the room almost completely filled with Hover panels. Being a Light Blade, it can be equipped by Isaac, Felix, Garet, Jenna, Ivan, and Piers. Phaeton's Blade's Unleash attack is Light Surge. Light Surge converts all damage to Jupiter damage and attacks with an additional 51 damage points. Also, there is a chance that it will cause delusion in the target. Visually, Light Surge resembles a multitude of light beams descending upon the target.

In Dark Dawn, Phaeton's Blade is found in a treasure chest within Snowdrift Shrine. You must slide down using the 5th slide-able hole right to the left and fall down into a larger slide-able hole. It now has a total of three Unleashes, due to Dark Dawn's revisions to the Unleash system. The first Unleash learned is Combat Dance, a non-elemental physical attack that multiplies damage by 1.5. The second Unleash is Light Surge, which it has retained from The Lost Age. Interestingly, this makes Phaeton's Blade one of the few weapons that doesn't have its Unleash from the first two games as its final learned Unleash. Instead, the final Unleash is Centurion. Centurion is a physical attack that converts all damage to Jupiter damage, and multiplies the damage by 2.4. It also has a chance to ignore 50% of the target's defense.

Analysis
In The Lost Age, Phaeton's Blade is the second strongest weapon at the time it can be obtained (the strongest is the Rising Mace), but it isn't long until  stronger weapons become available. However, Isaac and Felix's teams join forces after Jupiter Lighthouse is cleared, meaning there are twice  as many Adepts to pass the Blade on to after it is replaced. Since Light Blades can be used by so many Adepts, it will probably remain in  someone's possession for quite some time, perhaps even until Mars  Lighthouse.

Phaeton's Blade is given a massive improvement in Dark Dawn solely due to its new Centurion Unleash. Centurion's 2.4 damage multiplier is among the very best, its chance to ignore 50% of the target's defense notwithstanding. If both the user and the victim have max stats, it's peak damage is the highest of all unleashes. As Dullahan is weak to Jupiter and has comparably high defense, it might even outperform the Tisiphone Edge in this fight.

By the end of the main portion of the game, Karis, the only Jupiter Adept that can equip Light Blades, will most likely have the Verdant Sword, which gives a higher attack increase. Eoleo and Amiti will most likely possess the Herculean Axe and Masamune respectively. However, Phaeton's Blade is a good match for Himi, particularly if the player puts her in the Master class. The class will increase her Jupiter Power, as both Centurion and Light Surge are Jupiter-based, while the Master's high attack will increase Centurion's Power. After the final boss has been defeated, it is up to player preference as to keep the Phaeton's Blade or equip the Tisiphone Edge in its place.

Cultural Reference
Phaëton was the son of Helios, the sun god. Phaeton went to the heavens to ask Helios to confirm that he was his father, and Helios swore on the river Styx that he would give Phaeton anything he asked for in order to prove this true. Phaeton requested to drive his father's chariot (the sun) for a day, and despite Helios's attempts to talk him out of it, he was adamant, and the sun god relented. However, Phaeton was unable to control the fiery horses that pulled the chariot, and first drove too high, giving the earth a chill. Then, he dipped too low, burning the vegetation, turning part of Africa into desert, and burning the skin of the Ethiopians brown. Zeus was forced to intervene by striking the runaway chariot with a lightning bolt to stop it, and Phaeton died falling into the river Eridanos.

Trivia

 * The Phaeton's Blade is the only Light Blade (found not bought) that does not retain its signature unleash from previous games. It changes from Light Surge to Centurion.