it was to give bats some sort of way to stop supes, doent mean it'll work though.
imagine this right. supes starts off a mile from batman. supes accelerates to superpeed but bats has kryptonite. even with the kryptonite it will not sufficiently slow down supes before he hits (and probably kills) batman. supes would know bats has the ring, so he'd have thought of a way to get around it.
Dude, that means Superman is saying basically, "Without this(my weakness) you can't stand a chance"...
On a basic level Superman had to give Batman his weakness just so he'd "Stand a chance", that fact alone says that Superman would "destroy" batman is they fought "straight up" no gimmicks, cheats or weaknesses...
You can defend Batman until your face turns blue but Batman is just not on Superman's level...Face it
Batman ise good and under some circumstances he might actually have a chance to take down superman. But If they woukld walk down a road and supes just decides to fightr with Batman there is no way Batman can do anything.
Oh and I really found it funny that Superman carries a kryptonite ring around in hos belt, really funny. And I belive everytime there is just the slightest chance Batman would meet Superman he takes Kryptonite with him, thats just Batman it would be strange if he wouldn't.