Symbol: The Chair
Near the beginning of Act I, Scene 4, a very big deal is made about Edward allowing Gaveston to take a seat. To modern readers, it may seem strangely superfluous since there are stage directions to indicate the specifics of the act. What is going on is, though, is that Gaveston is sitting in a chair reserved exclusively for the Queen. Thus, the chair becomes a very blatant symbol of the king replacing his wife with Gaveston, both sexually and politically.
Symbol: Lightborn
The assassin hired to actually murder Edward is a fictional invention by Marlowe and his name is purely symbolic. The intricacies of his name are infused with typical Renaissance wordplay. It has a connection to Lucifer, yes, but as an ironically symbolic name, the connotation is much more potent. Much as a bald man might be nicknamed "Curly" or a tall man "Shorty," this man “born of light” is easily the most despicably malevolent character in the play.
Symbol: The Devices
Lancaster and Mortimer explain what their devices (emblems) are, which ostensibly seem like scenes from nature but are actually highly symbolic of their view of the situation in the kingdom. Mortimer describes a tall tree with kingly eagles, which symbolizes the kingdom and the nobles and the king. He then says there is a canker spreading through the tree, however; this is a symbol of Gaveston. Lancaster describes a flying fish whom the other fishes hate—Gaveston—and who is eaten by a fowl—perhaps the nobles. Both of these devices are vivid images in which the elements featured are symbolic of rot, idiocy, and baseness.
Motif: Decapitation
Almost all of the nobles are decapitated, including Mortimer, whose head will rest on Edward's hearse at the behest of Edward III. Much is made of the heads shorn from their body and how they will be warnings for other rebels in their adornments of pikes. Decapitation is a way to put someone to death, yes, but it is also more than that. It is evocative of severing off something corrupt, something dangerous. In the use of the heads after death, it is a very public condemnation of what it was that led to the decapitation in the first place.
Symbol: The Crown
A crown is not just ornamentation but a classic and powerful symbol of royal rule itself. When Edward is in prison and asked to give up his crown both figuratively and literally, he is reluctant, taking the diadem off and then putting it back on, hoping to be king for just one more night. Since the physical object of the crown is such a potent symbol of the rule itself, Edward imagines that if he can keep the object on his head that he will still be the actual king. When he surrenders the object, he surrenders all power and resigns himself to his fate.
