What are examples of diction in "The Devil and Tom Walker"?

When asked to analyze diction, one is meant to consider the words selected by the writer and how those words impact the experience of the story. For "The Devil and Tom Walker," Washington Irving uses a higher than average diction level, and there are many examples that exhibit his sophisticated vocabulary. One such example from early in the story reads,

It was late in the dusk of evening when Tom Walker reached the old fort, and he paused there awhile to rest himself. Any one but he would have felt unwilling to linger in this lonely, melancholy place, for the common people had a bad opinion of it, from the stories handed down from the times of the Indian wars, when it was asserted that the savages held incantations here and made sacrifices to the Evil Spirit.

In this quote, descriptors like "unwilling to linger" and "melancholy" are much higher diction choices than words such as "not wanting to stay" or "sad." In addition, the nouns in the passage are specific and related to particular worldviews or understandings. They are nearly jargon. These nouns—"savages," "incantations," "Evil Spirit"—are not words a person of minimal understanding would use. They reveal the narrator as educated or experienced with the world of superstition or legend. This sophisticated language makes the narrator seem more reliable or at least more entrenched in the world of the characters than the reader is likely to be.

Irving uses such language throughout the piece, and any passage from the text that uses such descriptors or jargon-like nouns would count as an example of diction.

Which names or phrases in "The Devil and Tom Walker" describe the Devil?

There is a brief passage that involves the discussion of the black woodsman's identity, but he is never specifically named as the Devil; in fact, in a later exchange between them, Tom says he'll send people "to the Devil" as though he were unaware that the Devil is the woodsman - although I think in this case Tom is just using a grandiose figure of speech and is perfectly aware of who he's dealing with.

The woodsman is described as being literally black, as though painted black, with a soot-smeared face that one would expect to find on a blacksmith. His hair is black, coarse and unruly, and he has red eyes. He wears a "half-Indian garb", meaning that his clothes are some mix of a woodsman's typical attire and Native American elements, with a red sash or belt, and an axe. He has a growling way of speaking and can be somewhat polite but also appear scatterbrained or preoccupied.

He is also described, or attributed, more explicitly supernatural abilities, such as burning his fingerprint into Tom's forehead, and appearing to sink into the earth.

Other names he is given include the "Wild Huntsman", "Black Woodsman", and "Black Miner", but Tom identifies him as "Old Scratch". Scratch appears to consider all of these names of equal value and doesn't really attach special significance to them.  

Are there examples of diction in "The Devil and Tom Walker"?

Diction can be defined as the style of speaking/writing that a person uses. It is determined by word choice. Based on that definition, yes, "The Devil and Tom Walker" uses diction, because the author has chosen specific words to tell the story. However, an author's use of diction is what separates good writing from bad writing. Diction serves a purpose. It has to fit with the story, characters, and target audience. When diction isn't properly used, readers can become distracted from the piece or even misinterpret entire messages within the text.

In "The Devil and Tom Walker," Irving uses a combination of formal and informal (or even colloquial) diction. The following is a good example of Irving using formal diction when describing a location.

Any one but he would have felt unwilling to linger in this lonely, melancholy place, for the common people had a bad opinion of it, from the stories handed down from the times of the Indian wars, when it was asserted that the savages held incantations here and made sacrifices to the Evil Spirit.

Notice words like "incantation" and "melancholy." Those words are not necessarily words that audiences wouldn't recognize and understand; however, they also are not words that are typically used in everyday conversation.

Contrast the previous narration with the following dialogue between Tom and the Devil.

"What are you doing on my grounds?" said the black man, with a hoarse, growling voice.

"Your grounds!" said Tom, with a sneer; "no more your grounds than mine; they belong to Deacon Peabody."

Notice that these words are much more common to everyday speech. Additionally, notice how the syllable count of the words falls off. Most of them are single syllable words. It wouldn't make sense to use the high formal language of the previous quote in a discussion between two men in the woods. This is especially true knowing that Tom is a miserly and miserable man to be around. He is gruff and rude, and formal diction simply wouldn't make sense from him.