Batman v. Superman, coming in 2016 is much anticipated for. Many theories have been emerging as to what Batman has been holding in his hands, not on the rooftop scene shown in the trailer, but the scene where he is shown standing alone in what seems like a destroyed Wayne Manor. He seems to be holding something in his hands. Seeing how this film will pit Batman against Superman, the rumor that Batman may be holding an Kryptonite laced spear may be true. According to Heroic Hollywood, the weapon Batman is shown holding is a “Kryptonite laced spear”. If you haven't seen the pic in the trailer, here it is:
And to compare:
This picture is a promotional image of the popular game, Injustice: Gods Among Us. The green "thing" Batman appears to be holding is also a Kryptonite laced spear which being Superman's weakness, may defeat him.