Of a Wizard's arsenal, the magic staff is probably the most useful. It allows the user to focus her power through it, reducing the cost to cast a spell by the user's level. They can come in all shapes and sizes, some magic-users prefer to have a wand, crystal ball or walking stick.
There are three types of staff: ordinaire, the regular enchanted staff with the powers described above, makeshift, a staff enchanted by the delver but which burns out after time, and the deluxe, a semi-sentient, almost indestructible staff which remembers every spell cast through it. These staffs were created by a small sect of powerful wizards, their construction a closely guarded secret.
Over at Vin's Trollbridge forum, some of the members have been throwing around some good ideas to flesh out the deluxe staff with new rules. Majyc made a good suggestion that the deluxe staff contains the mind and power of the first wizard that made it. This means that a new staff would come equipped with some powerful spells already installed, rather than forking out 5000 gold it only to find there is nothing in it.
A question was raised about whether the magic-user could learn the spells from the staff or do they need the staff in order to cast the spells. I would say that, being semi-sentient, the staff can remember the spells but isn't able to communicate them to the wizard directly. However, Majyc suggested that there could be a way of learning spells from the staff, but it may involve seeking out a great mage from the guild or compromising with the staff to teach the user a certain number of spells. Either way is good, it depends on the GM.
I would rule that any level wizard can cast these spells using the staff, but if the wizard's level is less than the level of the spell being cast they should roll a saving roll on the average on IQ and CHA (mahrundl's suggestion). If they fail the SR, the spell fizzles and the WIZ is used up.