I thought that was just to keep Adam and Eve out. And kind of like The Arc of the Covenant later on. At the time of the Jews wandering their way to the Promised Land, it was strictly forbidden to touch the Arc. If anyone touched it, instant death, but later on, things changed and the temple where it was stored was raided and the Arc was stolen. So I wonder if the angel at The Garden of Eden was removed, too. Alot of things changed AD.
It's not specific. Genesis 3:24 So he drove out the man; and he placed at the east of the garden of Eden Cherubims, and a flaming sword which turned every way, to keep the way of the tree of life.