Once again, you ability to make no sense astounds me. Why are you talking about things you don't have? Let's see. I need to enhance slow, so there's my magian earth staff. Next, I need to cast thundaja. There's my thunder magian staff for that. Lets just say those are the only two things I ever need to do, and I only have those two staves. I have to choose between casting slow with the earth staff, and casting thundaja with the thunder staff. Two different situations each calling for a different piece of gear.

Like I said for the 50th time, unless you only ever need one staff, you will need to switch between one or more weapons, and thus (3) is fufilled.

Evisceration
Is not something you find on a staff. whoa, we're making less and less sense by the sentence.