Answer- Henry seeks to engage his audience by showing his respect for them. He recognizes and compliments the patriotism and abilities of the other members of the Convention in his first sentence (note that Henry continues to address the body as the House). He prepares his audience by expresses the hope that they will show him the same respect when he states in sentence 2, "I hope it will not be thought disrespectful..." Even though he will be speaking contrary to what has been previously presented, he reminds his audience that they are all colleagues by referring to the entire group, as in sentence 6, "we can hope to arrive at the truth."
The phrase "awful moment" means a moment of great importance in the context. Henry uses this phrase because he wants to establish to his audience the great importance of acting upon the constraints and unjust of the British. Henry displays an idea that the American people should fight back against the British.
