Unless you don't pay attention to any document dropped in the game, and not check every room, you maybe could miss the blue dragon, although it's kinda hard to do. Dragons aint flies. There's 2 special areas before Klauth areas, and if you checked them both, then there's simply no way you could have missed the Blue Dragon. In that same room you can find the dragon sphere. Which leads to obvious conclusion - if you did read the notes, obviously - as to what your next step should be.
The resulting item makes the fight easier, when you offer it to Klauth. He'll be pretty beaten up from that right away, and the fight is much easier.
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