What is the justification for the nobility? Some appeal divine authority. In one world however, being of noble blood really does elevate you above the common rabble. By virtue of magical aptitude.
The dwarven gods true names can only be known by dwarves. They are referred to by nicknames in the presence of non-dwarves. I.E. Gudurran( Allfather) Baenna ( Hearthmother) Dudrak ( Ore), etc. No torture or magic or direct intent can reveal their true names to non-dwrves.