Here are two more rulings from DF Felltower I'd like to have in writing to refer back to.
Staff types are specific to caster type.
Clerical, Druidic, and Wizardly "staff" enchantments are available. They only work for the specific type. Multi-type staves (for those wizards with a cleric lens, or druids with a wizard lens, etc.) do not exist.
Restrictions on these items are very strict - I won't go into them all now, but suffice to say that most multi-purpose versions - "staff" on axe-handles, "staff" on bows, etc. are not allowed.
Power Items Are Not Shareable
Not a ruling, just a reiteration of a rule. You cannot borrow a power item, nor from the church's apparantly multi-user cathedral power item. Power items are not magical items, nor power reservoirs, for anyone other than the owner (DFRPG Adventurers, p. 115, makes this clear at the bottom of the box.)