Shulk's primary weapon throughout the entirity of the game is the Monado. This is a mythical sword of light, once used by the Bionis to fight the Mechonis. Because of this, it is the only known weapon which can damage Mechon. As this cannot be changed throughout the game, as with other characters, the attack power of the Monado increases with Shulk's level.
At the beginning of the game, the Monado is unable to attack, or harm, beings from the Bionis. However, the Monado is unshackled at Prison Island, giving it extra strength, allowing it to harm anything, be it from the Bionis or the Mechonis. This is the Monado II.
Towards the end of the game, Shulk loses the Monado. As such, Miqol creates a Monado replica. Proving effective, Vanea gives Shulk 5 quests to create 5 more Replicas, each of which specialising in different areas. These replicas are the Rudra (ease of use), the Agni (increased block rate), the Abyss (extra attack), the Dogma (high critical chance) and the Saga (high defence).
During the first playthrough only, when fighting the final boss of the game, Shulk obtains the 'True' Monado. Thisis the best of all of the swords in the game, with 999-999 attack, and all of the advantages of the Replicas. This is Monado III, and is a sword of light.
