The Magic Hoard: Staff Sphere

This is my first additive magic item - a term I'm using to describe a magic item that you add to another magic item for new/more power.

Staff Sphere: This small crystal sphere magically attaches or detaches from any magical staff at will. The bearer can cause the sphere to glow like a torch whenever desired and the glow takes a bluish tinge when facing north. Additionally, the bearer can use the staff sphere’s charges to charge the staff. When found a staff sphere has 2d6+2 charges. If emptied of all charges, the sphere cracks, falls to the ground, and shatters. Experience Point Value: 600 G. P. Value: 5,000