Like many Beastmen NMs, there is a 100% chance for something to drop. Hermit's Wand is the very common one, Priest's Robe is the rare drop (around 10%, I suspect).
It is not a 100% drop. First time I killed it, I got the robe, but not the wand. Second time I got the wand, but not the robe. I suspect that, like Onorgul suggested, it's a one-or-the-other drop.
Great club for BLU spell farming on weaker mobs. It has fairly low delay with which to feed TP, and very low damage that aids in keeping the mob alive until it uses the desired ability. The biggest bonus, however, is that with dual wield you have 50% spell interruption down.
For low-level mages this club is not bad. If you're not expecting to get hit, however, a Willow Wand +1 will give you one point higher MND and INT stats at a lower level (9), and at 18 the Yew Wand and +1 give a bigger bonus to both MND and INT (+3 and +4).