Corsair's Edge

Corsair's Edge is a Light Blade-class Artifact weapon in Golden Sun: The Lost Age.

In
It is initially found outside Lunpa's house in Lemuria as a Rusty Sword, requiring you to Scoop the tile with the buttefly. The Rusty Sword must be reforged in Yallam to gain the Corsair's Edge. As a Light Blade, Corsair's Edge can be equipped by Isaac, Felix, Garet, Jenna, Ivan, and Piers.

Corsair’s Edge's Unleash effect is Lunar Slash. Lunar Slash converts all damage to Jupiter damage and attacks with an additional 25 damage points. Also, it may decrease the target's elemental resistance by 40 (it can be further lowered to 80). Visually, Lunar Slash resembles the attacker jumping into the air and swinging Corsair's Edge, with a large slash cutting across the screen.

Corsair's Edge is surprisingly weak considering when it can be obtained. Stronger weapons will most likely already be available, such as the Mist Sabre and the Cloud Brand. In fact, this weapon is essentially a weaker version of the Ninja Blade, which can be purchased in Izumo. If stronger weapons aren't in the party's inventory, they can be received from the Lemuria Spring. As a result, Corsair's Edge will probably not see any practical use.

Cultural references
The word "corsair" is generally in reference to a French privateer, although it is also used as a more flamboyant or romantic word than "privateer" or "pirate." This reference probably has some association to the location it is found, Lemuria.