Deathstroke and Batman are after the same thing so of course they have to fight each other. Because Deathstroke's name is on the cover, Deathstroke comes out on top. Another valid reason for Deathstroke to beat Batman is if Batman's name were on the cover but it were only the first three parts of a four part story. Deathstroke makes sure to explain how he's enhanced and Batman is a normal person because he knows the reader is thinking, "Shaw! Right!" Deathstroke also says, "You've trained yourself to fight. I've trained myself to kill." I'm not sure how this comes into it since Deathstroke isn't fighting to kill Batman any more than Batman is fighting to kill Deathstroke. Although I did notice that neither of Deathstroke's sentences end in exclamation points which proves he does keep his emotions out of the battle! I can't even keep my emotions out of eating a burrito!