With an electric charge from his Cane he reanimates the dead. Equip your own Cane Stick (which you should have if you collect the Chalice from The Museum) and first take out the Zombies (quickest way is to charge your Cane with the button and let loose in the middle of them), then divert your attention toward him. He will be transparent and untouchable as long as there are Zombies still alive (he can still hurt you), but will solidify long enough to zap them back to life. As soon as he's solid, stay stationary and swipe at him with your Cane, one swing at a time. He will attack back, but will usually be too far away from you to score a hit. Five or six Cane swipes is all it takes.