There are many literary devices used throughout these lines. Here are some examples:
In line 126, Friar Lawrence tells Romeo, "Thy noble shape is but a form of wax." This is a metaphor, and he is basically saying that Romeo may look strong and honorable, but that he is melting or falling apart under pressure after killing Tybolt. He is comparing Romeo to wax because wax melts, becomes soft and, eventually, will burn away when under heat. He is saying that Romeo needs to be strong and hold it together.
In line 142, the Friar tells Romeo, "Happiness courts thee in her best array." This is an example of personification, because he is giving the feeling of "happiness" human-like qualities by saying that it is dressed up and "courting" (beckoning) Romeo. He is lecturing Romeo for not appreciating the good fortunes of his life.
He uses a simile in lines 132 when he says, "Like powder in a skilless soldier's flask." Here he is saying that by killing Tybalt and behaving so emotionally, Romeo is defeating himself.