I do not even feel like I have the tools to defend myself against his knowledge. That is what is giving me all the stress.
That would make perfect sense... if your thesis was in the discipline of Defence Against the Dark Arts.
If someone on your committee will act like it was a confrontation or a battle, that doesn't make them fit for that duty. So, I sincerely hope that nobody during examination will be openly antagonistic and trying to belittle your work. That's not the way to act, and none of that would be your fault. If they only noticed problems with your work during the examination, they have missed their chance at being useful. That's also why it's important that you make sure the committe is acquainted with the current draft of your work, and that you get as much feedback as you can ahead of the examination. Even the strongest critique - should there be any need for that at all - can be delivered in a professional and courteous manner. Academic environment is also about teaching - that means bringing up successors into the field.
Being prepared for examination doesn't mean cramming. Rather it means knowing what to expect from the examiners by interacting with them previously, enough so that you can be fairly confident that they are familiar with your work, approach, style of presentation, etc. and seem comfortable with it. The examination should not have any surprises for you - not because you've re-read all the subject notes from the entire degree's worth of material one week prior, but because you have a feel for what the edxaminers care about, which of their interests may intersect with your work, and so on. It's more about the human side of things that having your mind full of facts.
Unfortunately, on the Master's examination of one of my peers there was an openly hostile examiner who for no good reason whatsoever tried to find everything wrong with the student's work only then in spite of being familiar with it ahead of time, and not really raising any objections earlier. In my opinion that is unproductive - never mind terribly stressful for everyone, and probably cringe-inducing in other, more level-headed examiners in the same room. This is bad behavior - being aware of it should at least help you understand that none of your work can justify that.