E&I are used outside of Limbo, but Rebellion seems to only be able to exist there. They might be made from the same material, but so far we see that the Revenant is a different firearm from E&I, since there is that shot of the shotgun being slid to him, which he picks up.
In one of the videos reviews, after Dante knocks out the Hunter, there's that shot of Dante remembering his mother and holding onto his amulet while the background changes - because he's leaving Limbo. While he's leaving Limbo, Rebellion is also fading away, just like the twisted Limbo-side of the world.
So as it seems, Rebellion only seems to be able to exist inside Limbo. Or, running on the current info available it seems to be - it's possible that info could change when the full game is released.