Commissioned by Batman, this blade of Gold Kryptonite was created by Firestorm as a failsafe against Superman. He would keep it on his person, hidden away in a lead lined pouch on his utility belt.
After Kal-El turned-on Batman, breaking the truce between their two factions, the Dark Knight used the blade in single combat against his former friend and ally. However, it was in the struggle, forcing Batman to take more drastic action, to capture and detain the tyrant.
An incredibly rare variant of Kryptonite, Gold Kryptonite could remove a Kryptonians abilities, leaving them vulnerable to harm. While short-term exposure can cause temporary power loss, extended periods in the ore's presence could render a Kryptonian completely impotent.
After brokering a temporary truce between the Justice League and the former members of the One-Earth Regime, Batman had Firestorm manufacture samples of this mineral, crafting it into weapons he could use should Superman turn on him.
One such weapon was a Kryptonite blade which Batman used to fight Kal.
