Vajra Mace

The Vajra Mace is a mace introduced in Golden Sun: Dark Dawn and can probably be regarded as the most powerful mace in the Golden Sun series. Thunder Lizards in Crossbone Isle drop it rarely, though the odds increase considerably if they are defeated with a Venus Djinni. As a mace-style weapon, the Vajra Mace can be equipped by Matthew, Tyrell, Rief, and Eoleo.

Just like the Fur Coat in Golden Sun, the Vajra Mace is not considered an artifact and can't be re-bought if sold.

Cultural References
In Buddhism, a Vajra is a short, double-sided weapon that can cut through anything and not be scratched itself. Vajra is a Sankrit word meaning both "thunderbolt" and "diamond."