Obsidian Glaive

The Obsidian Glaive is an Obsidian Weapon used by Ronin.

History
There is little to no info about the Obsidian Glaive's creation, other than the fact that it originally belonged to Hibiki before being stolen. It is also revealed to be a dangerous artifact from long ago.

Shadow of Ronin
Spoilers

Ronin used the Obsidian Glaive to steal the memories of the Ninja, but Sensei Wu stopped him from completely stealing them, and he escaped with the Glaive.

Ronin would also later use the Obsidian Glaive on the Serpentine, making them work for him.

Ronin once again used the Obsidian Glaive on Misako, making her too work for him, until Lloyd used his powers to destroy the Obsidian Glaive, freeing Misako (and others) from its effect.

Powers
The Obsidian Glaive has the dangerous power to steal and/or alter the memories of its victims. However, its effect can be reverted by either obtaining one of the Obsidian Weapons, or to destroy it.