He'll have trouble getting the vexing cane until he reaches around 45ish. Before that the off-hand off of the boss in the graveyard and also the hypnotic dagger off of Doan are a great caster combo.

The quest chain
Strength of the Treant
lvl 40 req
http://wow.allakhazam.com/db/quest.html?wquest=3129
For the horde there is a long quest chain in feralas which gives you a very nice caster weapon
is a complete ***** to do just for a weapon. It's a great reward if you're following a leveling guide for experience, but to do that just for a weapon would take you a couple hours and have you running all over the world. Do not do this quest just for the weapon. A complete waste of time tbqh.