> But I am wondering why I have got so few extra-special items? I have gone over the "secret" half of level 9 many, many times, not to mention the pool area of level 8, and all I've managed is two Assassin's Robes and a Wizard's Cap. Shouldn't there be more extra-special items this late in the game? Or are they all on level 10?

You probably could find all the special items on level 9, I think. I found a Knight's Suit on level 7 during my first game, in fact. Perhaps this is about as shallow as they appear; I was told I was lucky to find such an item that high up. But surely you'll find them with higher frequency on level 10, especially in the pools (and, it seems to me, on a couple of empty floor spots in Murkon's chamber).