Durability

 is a gameplay mechanic in Dark Souls.

Overview
There are three levels of durability, each of which affects the performance of the weapon:
 * "Normal": This is when the weapon is at optimum efficiency.
 * "At Risk": Once a weapon's durability reaches an "At Risk" status, it suffers from slightly reduced damage. A message informs the player that this status has been reached.
 * "Weapon Broken": This is when a weapon's durability has reached zero, and suffers largely reduced damage. In addition to a message, an icon under the player's stamina bar notifies them that the weapon is in need of urgent repair.