There are 5 arcane items and (although I'm no wizard), in my opinion all but 1 of them either have signifiant drawbacks, are not powerful enough or are too expensive.
My top pick of the lot would have to be:-
Skullmantle
This costs a mere 20 pts and deducts -1 from the leadership of any enemy that has to take any kind of leadership test due to the bearer of the skullmantle or any unit he (or she - do you get fenale Ogres ?) is with.
I think this is quite a nice little bargain for 20 pts. A warbanner costs 25 pts and that only affects combat resolution. This item is for break tests and all other leadership tests
Combine this with a nice powerful unit and we're taliking about the enemy failing a lot more leadership tests that they normally do (around 20% more, depending on their unmodified leadership)
So if you rout 1 enemy unit thanks to the effect of the Skullmantle in the course of a 5 turn battle then providing that enemy unit was worth 100 pts or more it was points well spent.
Just make sure you combine it well with other items which can improve your combat resolution.
