Putting character speech inside quotation marks is a good way to separate the narration and the speech. That way you don't always have to write "_____ said:".

Another good thing to try and do is put yourself in the mind of the character. What would he be thinking as he looked at David and the weapons? How does he walk? What kind of person is he? Is he naturally violent? More reserved? Would he attack first or bide his time? The more you can understand a character, the better you'll become at writing them.