Duke - Duchess

The Contested Lands have no shortage of self appointed "Dukes" some of whom put the lie to the term "nobility", likewise there are some factional "Dukes" who are not much better.
Of course though, the general rule is that Duke or Duchess control significant areas of land, resources and, importantly human power.

Type

Nobility, Household

Source of Authority

Often a title bestowed, however, there is no shortage of "self-appointed" duchy seeking self-importance.