Clipped from Superman Home Page: In "Superman Annual #10" (1984), the logo is again something Pa Kent dreamed up. However, Jonathan Kent apparently formed a psychic connection with the legendary "Sword of Superman". The sword formed during creation's Big Bang with an "S" logo emblazoned in its handle; this "Sword of Superman" floats around space for centuries until it finally comes into contact with Superman. When Superman grasps the sword, it begins to make him an all-powerful, all-knowing super deity. Superman rejects the sword's power so he can remain Earth's greatest hero.
Read an Article from Gone & Forgotten about the Sword of Superman: Why does everyone in the
universe know Superman, revere him and call him by his name, “Superman”?