[phiwum]

I wouldn't interpret that sentence too literally. It's just saying that wizards should use silver daggers. Iron daggers can't be staves and wooden daggers are no better than fighting with a stake, which surely does less damage than a proper dagger, maybe a point or two.

Are you seriously considering a character using a wooden knife as a staff? I'd allow flint knives as a possibility, with less damage than a proper dagger.

Aside: in the excellent solo adventure Vampire Hunter Belladonna, David Pulver interpreted silver stakes as equivalent to daggers. I'd make them unthrowable.