Like a steeple (Simile)
As Duke Leto comes out of his haze, “the memory of the false tooth stood out in his mind like a steeple in a flat landscape.” In this simile, the Duke's consciousness is revealed to be featureless and flat due to the drugs, with nothing in his mind except for one memory—the fake tooth with poison in it given to him by Dr. Yueh. His memory of the tooth is compared to a steeple, a religious comparison that indicates the memory's immense importance.
Time creeping like an insect (Simile)
Before the final battle on Arrakis, Paul “felt time creeping like an insect working its way across an exposed rock.” In this simile, Herbert emphasizes Paul's strange perception of time, comparing time itself to a killable animal making a slow, risky journey.
The litany against fear is a cool bath (Metaphor)
When Paul is afraid as he fights Jamis to the death, he recites the Bene Gesserit litany against fear: Fear is the mind-killer. Herbert writes that “It was a cool bath washing over him.” This metaphor emphasizes the relief created by the litany, and how it wakes Paul up, revitalizing him like cool water in the desert.
The rock profile (Simile and Metaphor)
“The faraway rock profile was like an ancient battleship of the seas outlined by stars. The long swish of it lifted on an invisible wave with syllables of boomerang antennae, funnels arcing back, a pi-shaped upthrusting at the stern.”
The above quotation has both simile ("like an ancient battleship of the seas") and metaphor ("lifted on an invisible wave"), using both rhetorical devices to paint an elaborate portrait of what's basically just a big rock at night. Herbert also uses devices common to poetry, such as consonance ("st" in upthrusting and stern), rhyme (invisible, syllable), and association ("pi" evokes mathematics and "syllables" evokes speech, neither of which are immediately related to large rocks). The literary devices here make the passage lovely and interesting to read, but they also tell us about the character who narrates the image: Paul compares the desert to the sea because he grew up on Caladan, a water planet, and invokes his own interests when looking out across Arrakis.
Light like the crysknife (Simile)
Lady Jessica looks out of the governor's mansion on Arrakis and observes: “the milky light of the Arrakeen sun gave the scene a silver cast—light like the crysknife concealed in her bodice.” Similes like this appear often in Herbert's writing, and they give the reader information in both directions: the simile paints the scene of Arrakis in a silver light associated with a weapon, and at the same time the simile describes the crysknife, associating it with that unfamiliar silver planetary glow.
