Consider Edward II as a play of the irony of kingship.

Kings are expected to be powerful figures, exuding authority and gravitas, bringing great glory to themselves and their kingdoms. Yet at the same time their immense power and wealth can just as easily lead them to a life of luxurious self-indulgence and dissipation which undermines their authority. This is the irony of kingship and the tragedy of Edward II's reign.
Edward consistently falls below the standards expected of a king. Instead of providing leadership he prefers to waste his energy on the endless pursuit of pleasure and luxuriating in the company of flatterers. He makes frequent unconvincing attempts at asserting his kingly authority, yet it's all so much hype and bluster. His threatening words to the pope are an example of this:

I will fire thy crazed buildings and enforce The papal towers to kiss the lowly ground. (Act I, Scene IV).

Yet in the pope's presence Edward's bravado evaporates. He's set a dangerous precedent indeed. Now that his nobles know that his tough words aren't backed up by action, they can take liberties with him. His weakness is there for all to see; he is a king in name only.
It says a lot about Edward's weakness that he constantly has to remind himself to live up to the standards of kingship. If he were a strong ruler, he'd simply act like one instead of talking about it. Talk is cheap, and it's no substitute for action, especially for a king. The more he obsesses over what he ought to do as king, the more Edward undermines his authority, so much so that it leads to widespread disobedience among his nobles and eventually his assassination.