Heh - BMF (lol, I like that) ...
I can fully understand. I knew not where Nessie was but knew the general area of her location (what 'zone' she was in) - so I was prepared and was still thrilled to find her (thought she looked awesome).
While beating her and checking the chest, I didn't get Excalibur. I even fought her three times. Didn't get it (and I had restored to outside).
My wife, who got Cane of Corpus (as did I, but didn't have any Ninja Faerie) and Excalibur.
So when I replay the game, I am gonna beat Nessie into the ground until she hands me Excalibur.