In Thomas Hardy's "The Withered Arm," of the several characters in the story, the two main characters in the story are Rhoda Brook and Gertrude Lodge. The narrator concentrates first on Rhoda, and later on Gertrude. 

Hardy's characterization is direct. Direct characterization takes place when the author...

...literally tells the audience what a character is like. This may be done via the narrator, another character or by the character him- or herself.

The author provides specific information regarding Rhoda, Gertrude and the others, through the narrator and other characters. The audience is given a mental image of the Gertrude's looks from Rhoda's son's descriptions, but we learn from our omniscient narrator how Rhoda feels about Gertrude when they first meet:

...her voice was so indescribably sweet, her glance so winning, her smile so tender, so unlike that of Rhoda's midnight visitant, that the latter could hardly believe the evidence of her senses. 

Another aspect of characterization is whether characters are well-developed or underdeveloped. The well-developed character...

...is one that has been thoroughly characterized, with many traits shown in the narrative.

These "round" characters would include Rhoda and Gertrude. There is more information relayed in the story with the well-developed characters.

...a greater sense of realism occurs if the characterization makes the characters seem well-rounded and complex.

Characters that are underdeveloped are...

...flat, shallow or stereotypical.

Rhoda's son is a flat character, and Gertrude's husband is underdeveloped as well. For instance, most of the description we receive of the farmer Gertrude married comes after her death:

Burdened at first with moodiness and remorse, he eventually changed for the better, and appeared as a chastened and thoughtful man.   

We learn about what he does after Gertrude's death: selling the land and livestock, and moving. We do not learn about the inner-workings of the man except from the little included above.

Of Mrs. Lodge, we learn much more with the author's narrative. First...

'I shouldn't so much mind it,' said the younger, with hesitation, 'if - if I hadn't a notion that it makes my husband dislike me - no, love me less. Men think so much of personal appearance.'

'Some do - he for one.'

'Yes; and he was very proud of mine, at first.'

...She tried to hide the tears that filled her eyes. 

We learn that Gertrude cares for her husband and his opinions of her, and we know she is also hurt and upset because she cries. Later...

'My arm.' She reluctantly showed the withered skin.

'Ah! - 'tis all a-scram!' said the hangman, examining it...

...'You can contrive for me all that's necessary?' she said breathlessly.

We know how Mrs. Lodge feels about her arm, with many references in the story. The narrator gives us other information as he describes how she speaks: talking to the hangman, she "reluctantly" shows him her arm, which lets us know she is embarrassed. When she asks him a question "breathlessly," the reader knows she is excited. Gertrude is emotional; she is hopeful.

The narrator provides many details about the women.

Characterization is also demonstrated in that the story is character-driven, focusing on the characters' personality, not the story's events. While the act of damaging Gertrude's arm is the major conflict of the story, the plot is driven by Rhoda and Gertrude, how they act and how they interact.