During the early renaissance, social hierarchy based on wealth became more prominent, but at the same time a poor nobleman still had a higher social status than a rich merchant. So how did the nobility maintain this hierarchy?
It all had to do with who held legitimate institutional power and until the proliferation of capitalism and liberal democracies all institutional political power derived from the monarch and their various historical relationships with different families. At a certain point there was a shift worldwide, and rich commoners (in the form of the bourgeois) began holding the reigns of all legitimate political power and nobility dissolved into irrelevancy.