I didn't see anything against it in the rules, but I was wondering what the rest of you thought of a focus item that also holds a few charges of a spell. It would still take up the appropriate number of slots in both categories. The rules cover items of either type taking up more than one slot, but not items that take up both types of slots.
Just as a hypothetical example (because my players read this forum):
Bob the Wizard's Staff
+1 Air Attack Complexity/Control
2 Charges of Air Shield at Power 4 for 2 rounds
This takes up 2 focus item slots, and two enchanted item slots.
The actual combination I'm planning fits the mythos of the character, but there's not exactly a canon example of this type of item... except maybe the blackstaff, but we don't really know how that works. In any case, I'm going to roll with it anyway. I was just curious as to what the rest of you thought.