What does the unnamed skull do in halo2

The Unnamed Skull strengthens the Artificial Intelligence of both allies and enemies. They will now notice the slight shimmer of active camouflage, shadows, the sound of reloading or drawing a weapon, footsteps, etc. All computer controlled characters have better accuracy and are much less likely to kill themselves or their teammates (the player for example) with the Rocket Launcher/Fuel Rod/Brute Shot.