Not much is known about this strange artifact, as it was only featured in the Champions of Meridell plot.
The Orb brought prosperity to Darigan Citadel, and later Meridell after being stolen. It's absence caused Darigan Citadel to become cursed and corrupted.
Eventually, The Orb was stolen back, but corrupted Lord Darigan's heart instead of healing the land. When Lord Darigan was defeated, The Orb was broken into two, destroying it, and preventing further war over The Orb's power.