What tone to use in your closing speech
I have found it incredibly difficult to find books on how to deliver speeches if you are a barrister, and in fact was only able to find one, called "Hints for Public Speakers - aimed at young barristers and students of law"413.64 KB written by T Knox in 1797. The following quote is from this book, and covers the tone you should use when opening.
The peroration (closing speech) – What tone to be used
You would do well (and Mr Erskine normally practises it with great effect) to make a considerable pause between this part and the former, and to begin it with a lower tone than that in which spoke the confutation. As you proceed a little you should break forth into a louder voice, and conclude your speech with a triumphal tone, upon an assurance that you have sufficiently made good your cause, and that to the satisfaction of your whole listeners. As Mr Erskine did in his glorious defence of the Dean of St Asaph in 1784.
“As the friend of my client, and the friend of my country, I shall feel much sorrow, and you yourselves will probably hereafter regret it, which the season of reparation is fled. (Now Erskine broke forth in a tone of full confidence that there was no reason to fear his success) But why should I indulge such unpleasant apprehensions, when in reality I fear nothing. I know it is impossible for English gentlemen, sitting in the place you do, to pronounce this to be a seditious paper; much less upon the bare fact of publication explained by the pre-fixed advertisement, and the defendants general character and deportment, to give credit to that seditious purpose which is necessary to convert the publication of libel itself into a crime.