Criteria for the 2nd Class was a single act of bravery in the face of the enemy or an action that was above and beyond the call of duty.
The 1st Class for the Army or Waffen SS required another 3 or 4 acts of conspicuous bravery whereas the Navy would award it to captains who had sunk in excess of 50,000 tons of shipping and the Air Force for 7 confirmed kills but it could be awarded for a single act considered of such importance as to warrant the award simultaneously with the 2nd Class as described by Kvalidir
The highest grade of the Iron Cross was the Knights Cross of the Iron Cross created in 1939 but more grades were created to recognise ever more significant actions and achievements. First was the Knights Cross of the Iron Cross with Oak Leaves in 1940 followed by the Knights Cross of the Iron Cross with Oak Leaves and Swords and the Knights Cross of the Iron Cross with Oak Leaves, Swords and Diamonds in 1941 followed by the Knights Cross of the Iron Cross with Golden Oak Leaves, Swords and Diamonds in 1944