Brian McKiernan is clearly a smart man. He rose through the ranks in Davy to become the chief executive of the stockbroker as well as its largest shareholder. Along the way, he amassed a personal fortune few could truly comprehend and developed a reputation as one of Ireland’s top financiers. But there is such a thing as being too smart. On Sunday, the Business Post published an interview with McKiernan, who was forced to resign as chief executive following a damning Central Bank investigation into an Anglo bond scandal in which McKiernan personally benefitted – a scandal that precipitated an…