How does Oedipus exhibit weakness of character? Point to lines in the play that reveal him as imperfectly noble in his words, deeds, or mistreatment of others.

In the play, Oedipus betrays much of his inner turmoil through his words and actions. His paranoia is particularly evident in his interactions with Tiresias and Creon.
When Tiresias reveals the truth about Laius's murder, Oedipus refuses to accept what he's hearing. For his part, Oedipus thinks that both Creon and Tiresias are conspiring to wrest his kingly powers from him. So, Oedipus attacks Tiresias verbally:

What spite and envy follow in your train! See, for this crown the State conferred on me. A gift, a thing I sought not, for this crown The trusty Creon, my familiar friend, Hath lain in wait to oust me and suborned This mountebank, this juggling charlatan, This tricksy beggar-priest, for gain alone Keen-eyed, but in his proper art stone-blind. Say, sirrah, hast thou ever proved thyself A prophet?

Oedipus's words above reveal his weakness of character. Instead of investigating Tiresias's claims, Oedipus resorts to ad hominem attacks against the prophet. It's obvious that Oedipus feels threatened by what he's hearing. He refuses to acknowledge any possibility of his involvement in Laius's death because his self-image is encapsulated in his kingship. Tiresias's words threaten that very kingship, so Oedipus lashes out in anger.
Later, Oedipus reacts much the same way with Creon. He accuses Creon of having put Tiresias up to accusing him of Laius's death. For his part, Creon tries to reason with Oedipus, but to no avail.

Thou art glib of tongue, but I am slow to learn Of thee; I know too well thy venomous hate.
If thou dost hold a kinsman may be wronged, And no pains follow, thou art much to seek.
When with swift strides the stealthy plotter stalks I must be quick too with my counterplot. To wait his onset passively, for him Is sure success, for me assured defeat.

From Oedipus's words above, we can see that his habit is to act swiftly and without forethought when threatened. Prior to his exchange with Creon, we see Oedipus's paranoia on full display. He finds secret meanings in Tiresias's words; every innocent phrase is fraught with a hidden insult or threat, and every motive is imbued with malice. It is Oedipus's paranoia that leads him to make poor decisions throughout the play. Here is how Creon answers him:

Now all men cry me Godspeed! wish me well, And every suitor seeks to gain my ear, If he would hope to win a grace from thee. Why should I leave the better, choose the worse? That were sheer madness, and I am not mad. No such ambition ever tempted me, Nor would I have a share in such intrigue. And if thou doubt me, first to Delphi go, There ascertain if my report was true Of the god's answer; next investigate If with the seer I plotted or conspired, And if it prove so, sentence me to death, Not by thy voice alone, but mine and thine. But O condemn me not, without appeal, On bare suspicion...

Creon lays out the rational path for Oedipus, but Oedipus rejects it. In this, Oedipus exhibits weakness of character. Can you see other ways Oedipus is less noble than he makes himself out to be? Refer to his exchanges with Jocasta to add to your answer.