ITA, Chris. Further, I believe GZ exposed or brandished his gun and grabbed hold of Trayvon in an effort to detain him and Trayvon was fighting for his very life. Perhaps he got the wounds on his hands from wrestling with the gun. But even if he pummeled GZ, he was justified as he was standing HIS ground out of fear for his life from this stranger who pursued and confronted him with a weapon.
I just have a hard time believing this scenario when men 3-4 times the size of TM will cower at the very sight of a gun when it's pointed at him. Why would GZ need to 'detain' TM once he had his gun pointed at him? At that point, for all intents and purposes, TM was detained.