The item he's likely talking about is the cane of corpus. You can usually get one if you kill the Rattkin Don who steals the Astral Dominae from the Dark Savant.
The cane does a very high amount of damage, has a 50% of paralysis and a 100% chance of a strong poison attack. However it can only be used by a faerie ninja, nobody else. It's also cursed so you can't swap weapons without uncursing first. Not exactly much of a penalty since by the time you get the cane you'll be able to cast spells although you won't be able to use the ninja's ranged critical ability.
As for the bishop's turn undead skill. I've never found it to be particularly strong and generally just does a bit of damage to nearby undead. I don't always use it though and undead aren't that prolific.
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