Batman v Superman "“ the Kryptonite

Man of Steel didn't include this rock "“ but Batman v Superman will. And it isn't like we heard before "“ it isn't in the possession of Bruce Wayne, but in the possession of Lex Luthor. Sure enough, the rumor is that Batman will pay a visit to Lex Corp and actually steal the kryptonite. Another rumor would be that Bruce Wayne will ask for it from Lex"¦
In any way, the big question as to why Superman kneeled in front of Lex is answered "“ it was just this rock.

Of course, an even bigger question would be this: how does Lex know that this is Superman's weakness? How does Batman know, especially if he is said to have his mech suit lined with kryptonite?

Does this have anything to do with those soldiers with an S insignia?
On the next page, the money shot!
