In Geoffrey Chaucer's "The Wife of Bath's Tale," from The Canterbury Tales, I find that while he learns the answer to the riddle, the knight is much the scoundrel he was at the beginning of the tale—in that he raped an innocent woman.
In the story, the knight is taken before King Arthur. The penalty in those days, the poems states, is execution—his beheading:
He saw a maiden walking through the corn,
From whom, in spite of all she did and said,
Straightway by force he took her maidenhead;
For which violation was there such clamour,
And such appealing unto King Arthur,
That soon condemned was this knight to be dead
By course of law, and should have lost his head,
Peradventure, such being the statute then... (29-36)
We know, too, that the Queen intercedes on the knight's behalf, offering to spare his life if he can discover what it is that every woman wants. This is what the Wife wants the men in her company to learn—and also that an unattractive woman (such as herself) can be a surprisingly fine lover—which supports her desire to marry for the sixth time.
So the knight takes a year to find the answer, coming upon it on the last day: offered by a hag—in exchange for one wish. He agrees, tells the Queen and court the answer, and is released. However, the hag now claims her right—her wish is to marry the knight. The knight tries to make a last minute deal that she take his money and not his freedom. She refuses. Ironically, now the knight decides to be honorable—and he sticks to his word. They do marry, but then he complains because she is so ugly and "lowborn."
You are so loathsome, and so old also,
And therewith of so low a race were born,
It’s little wonder that I toss and turn.
Would God my heart would break within my breast! (185-188)
In my view, the knight is given the easy way out: having committed a ruthless and dishonorable deed in the first place, he is pardoned. Now he whines because the woman who saved his life is not attractive.
The old hag (his wife) gives him a choice: he can have her old and ugly and never have to worry about her fidelity, or she can be beautiful but he will never know if she is being faithful to him. This "choice" actually provides the audience a chance to see how well the knight "learned his lesson."
“Choose, now,” said she, “one of these two things, aye,
To have me foul and old until I die,
And be to you a true and humble wife,
And never anger you in all my life;
Or else to have me young and very fair
And take your chance with those who will repair
Unto your house, and all because of me,
Or in some other place, as well may be." (224-231)
The knight, being a smart young man (as the Wife wants her audience to believe) lets his wife make the decision for him.
My lady and my love, and wife so dear,
I put myself in your wise governing;
Do you choose which may be the more pleasing,
And bring most honour to you, and me also.
I care not which it be of these things two;
For if you like it, that suffices me. (235-240)
With this, the hag turns into a beautiful woman who promises also to love him always:
And when the knight saw verily all this,
That she so very fair was, and young too,
For joy he clasped her in his strong arms two,
His heart bathed in a bath of utter bliss;
A thousand times, all in a row, he’d kiss.
And she obeyed his wish in everything. (255-260)
The knight simply performs a function for the tale's moral: a passive receiver, he is no hero, but shallow to the core.