The Swords of Eden were sword-like artifacts created by the Isu. These Pieces of Eden seemed to grant their bearers great power and leadership, and were most commonly used by influential humans in war and conquest.
Several conquerors and heroes in human history had been in possession of a Sword of Eden. Their users appeared to be capable of negating the effectiveness of illusions created by Apples of Eden, translocation, a form of echolocation akin to Eagle Vision, and the ability to project energy blasts at their foes.
During the 5th century, a Sword came into the possession of Attila the Hun, after a shepherd unearthed it and gave it to him. With the Sword, Attila ravaged Eurasia during his reign, and over time the weapon became known as the Sword of Mars or the Sword of Attila.
During the late 6th century, a being claiming to be the Norse god Odin, disguised as a beggar, plunged a Sword into a tree called Barnstokkr, stating that whomever was able to pull it free would receive it as a gift. Only the warrior Sigmund proved able to do so, and subsequently claimed the Sword as his own.
During the early 13th century, the Mongol warlord Genghis Khan led his Empire through mass expansions into the West. The Mentor of the Levantine Assassins, Altaïr Ibn-La'Ahad, suspected Genghis Khan of wielding a Piece of Eden, presumably a Sword. Altaïr's son, Darim, and the Mongolian Assassin Qulan Gal killed Genghis Khan in 1227. The artifact remained in Mongol hands however, and Hülegü Khan used it in his conquests of the Levant during the 1250s, notably during his attacks on the Assassin strongholds in Alamut and Masyaf.
By the early 14th century a Sword was in possession of the Knights Templar. After the Templars were branded as heretics in 1307 by Pope Clement V, and the Parisian Temple was attacked by King Philip the Fair's forces, Grand Master Jacques de Molay entrusted his advisor with hiding the Sword and the Codex Pater Intellectus, a book written by de Molay. The Sword was briefly in possession of the Master Assassin Thomas de Carneillon, who attempted to steal it along with the book during the attack on the Temple.
However, the Assassin was defeated in combat with de Molay's advisor, who used the Sword's power to project an energy blast at de Carneillon, before hiding both artifacts in a vault beneath the Temple, where the Codex remained entombed for four centuries.
In the early 15th century, a French peasant girl, Jeanne d'Arc, discovered the de Molay's Sword and took ownership of it during the Hundred Years' War, entering into the war on the side of the French forces. Becoming into a heroine of her people, Jeanne led the French to many victories over the English and their allies. However, she was eventually captured by Burgundian soldiers and handed over to the English. The Templars then burned her at the stake, in order to take possession of her Sword. This particular sword was named "Piece of Eden 25" by Abstergo.
In the later half of the 16th century, a Sword of Eden wound up in the hands of the Japanese warlord Takeda Shingen. With the power of the artifact at his disposal, Shingen began making his way to the capital of Kyoto to conquer Japan. Several months after routing Tokugawa Ieyasu's army at the Battle of Mikatagahara, Shingen was killed in a raid led by Ieyasu's vassals, the Assassin Hattori Hanzō and Honda Tadakatsu. The artifact was eventually obtained by Ieyasu's ally, Oda Nobunaga, who in turn used it to conquer the lands of other warlords. When Nobunaga's vassal Akechi Mitsuhide betrayed Nobunaga and attacked him in Kyoto, Nobunaga was killed by the Assassin Yamauchi Taka and the artifact was transported to China by Liu Yan.
In 1794, during the French Revolution, the Sword of de Molay was acquired by François-Thomas Germain, the Grand Master of the extremist faction of the Templar Order. Germain used the Sword during his fight with Arno Dorian and Élise de la Serre. The Sword was damaged in the confrontation, shattering and emitting a shockwave which killed Élise and mortally wounded Germain himself. Following the event, the Sword ended up in Arno's possession, though while it no longer possessed its former powers on account of the damage caused in Élise's final charge, it remained as one of the most powerful weapons in Arno's arsenal.