Why is the high King not giving titles to his sons? Why are the dukedoms and counties and baronies not hereditary for the high Kings family? Far in the past, the title of Arch Duke and Duchess was given to the direct heirs, causing their territories to be used in wars of succession. Grandchildren, nieces, nephews, etc. were given titles and used this to levy tax and start conflicts. The ‘princes of the blood’ have a history of violence. A history of blood, turmoil, and succession wars.
There is No Arch-Duke Peerage of the Realms. To prevent the past turmoil of succession politics, the Charter of the High King states that the High King of the Steel Realms shall raise no family member to Peerage greater than Knight.