How powerful is the wand of water in the Cloak tower?

My Rogue(2)/Bard(5)is having problems using the wand of water in the Cloaktower.

He collected the 4 ingredients for the first test. Eltoora sends him to a chamber with four wands and a Minoton. The Bard grabs the wands and starts to use them on the Minoton. He is successful with the earth, air and fire wands. When he uses the water wand he gets the message "... cannot use wand..." (the Minoton goes on to stun, then destroy my character with amazing ease... :( )

**sigh**

Reload to just before I talked to Eltoora (I save often); buy a Nymph Cloak with whatever cash I can scrape together; with the Belt of the Performer, Lantanese Ring and a potion of Eagle's Splendor my Charisma is boosted to 23 and Use Magic Item goes up to 17. Success! I can use the wand this time. If I had not done all the henchmen quests first I might be SOL.

It seems to be a high level item that according to it's description has only one charge and is only usable in the Cloaktower...