Junk Sword

The Junk Sword is the weapon used by for the first bit of Xenoblade Chronicles. It is a simple sword he crafted before the game began.

While there is nothing stopping Shulk from selling or unequipping the Junk Sword, he cannot do so as there are no other weapons for him to equip instead. Once Shulk gets the Monado, the Junk Sword is deleted.

Trivia

 * There are some unused variants of the Junk Sword that suggest at one point Shulk had options between different weapons before obtaining the Monado. This would explain why the Junk Sword can be unequipped and sold.