The merchant is an indirect characterization by means of a third-person narrator using the technique of telling. 

The speaking voice creates a negative characterization of the merchant by means of different strategies throughout the text. All of them have a negative connotation and add to the characterization of the merchant.

The most frequent strategies used are: irony and ambiguity. Irony is expressed by exaggeration. Those strategies are used within others: reputation, physical appearance, dressing style, way of speaking, and working skills. 

When Chaucer criticizes the merchant in truth he wants to criticize the materialistic attitude of the middle  class. 

THE KNIGHT 

The knight is an indirect characterization by means of a third-person narrator using the technique of telling. 

The speaking voice creates a positive characterization of the knight by means of different strategies throughout the text. All of them have a positive connotation and add to the characterization of the knight.

The poet uses different strategies in order to create a positive characterization of the knight.

The different strategies used are: reputation, medieval values  (chivalry), narrator’s personal judgement, riding skills, battles, humility, way of speaking and religion.

All those strategies provide a positive connotation of the knight but all of them sound a little exaggerated. All the strategies used to create the characterization provide a feeling of perfection that doesn't seem real.

The merchant is a negative characterization while the knight is a positive one. 

In both characterizations the poet uses exaggeration but in the characterization of the knight exaggeration is used to connote the character in a positive way while  in the characterization of the merchant the poet  uses exaggeration to connote the character in a negative way.

Chaucer wrote “Canterbury tales” to criticize and highlight mediaeval values. 

Therefore after reading “the merchant” and “the knight” we can understand that Chaucer celebrates 

 the medieval chivalry and criticizes  the middle class.