there is more than 1 Master Key in the game and there is 1 Wizard's Virge.
These items are either hidden or you need special keys to get them, however in the case of the Wizard's Virge, if you get the Master key then locks won't stop you.

Gaining these items is quite a challenge and holding onto them an even greater challenge. It may be best to just skip the opportunity to get either or both of these, life in the Dungeon could be a little more sane without them :)