Final answer:
A king's trust in Duban over the vizier can be compared to historical tendencies where rulers favored loyal and proficient individuals devoid of conflicting interests for positions of authority, as exemplified in the Mamluk and Persian governing systems.
Step-by-step explanation:
The king should have trusted Duban more than he trusted the vizier due to the principle of loyalty and expertise presented in historical contexts. Medieval rulers like the Mamluk sultans preferred loyal mamluks because they were trained and indoctrinated to be loyal to their benefactor, whereas the offspring of the nobility might pursue their own family interests.
Similarly, in governance structures from Persia to feudal states, kings appointed trusted officials or governors who would remain loyal and enforce the king's policies, without personal interests conflicting with the ruler's authority. Medieval governance often relied on individuals who were not only expert but also had a clear line of loyalty to the ruler, as seen in behaviors of nomadic chieftains and the Persian satrap system.