Vajra

Vajra (ヴァジュラ) is a symbol of divinity of Indra, the god of lightning from the Vedic mythology of the ancient India, and the indestructible diamond pounder (金剛杵, Kongōsho) weapon carried by the gods of Buddhism. Vajra was initially known by its proper name of Vjaya when Indra was first introduced to India as a phenomenon that spread from the Aryans. Along with Indra, whose name changed to Taishakuten, his divine symbol also had its name changed and became known as Vajra after the age of Buddhism as India's main religion began.

It is a diamond-shaped object imbued with lightning that upon contact with a formidable physical surface, violently explodes, causing blades of lightning to ripple out and burn through whatever lay in their path.