Early in the play Helen speaks to the King, using metaphor and alliteration as tools of persuasion as she asks him—if she succeeds in curing his illness—to let her choose her own husband:
Then shalt thou give me with thy kingly hand
What husband in thy power I will command.
Exempted be from me the arrogance
To choose from forth the royal blood of France,
My low and humble name to propagate
With any branch or image of thy state;
But such a one, thy vassal, whom I know
Is free for me to ask, thee to bestow.
In this passage Shakespeare makes Helen’s speech to the King sound almost like a song by using alliteration. This is a literary technique in which words that are close to each other start with the same sounds. The letters can be different as long as the sound is the same, as it is here in “kingly” and “command.” This makes Helen’s plea to the King seem more heartfelt and serious. This effect is magnified by the slow, distinguished rhyme scheme of the couplets she’s speaking. The “K” sound in “kingly” moves from the "possession" of the King to being in Helen’s grasp as she says the word “command.” In this way, the alliteration used here represents Helen’s request for a transference of power and autonomy.
When Helen talks about wanting her “low and humble name to propagate with any branch,” she's using gardening terms and the language of growth as a metaphor to talk about marriage and fertility. The word “propagate” usually means to create new plants, and “branch” refers to part of a tree. She wants to marry into the King’s court to better herself, and to grow and tend her “low and humble name.” In so doing, she’ll “propagate” children and grow into nobility.
In this scene, the First and Second Lords and Bertram discuss a plan they have to expose Parolles as a coward. The First Lord uses alliteration and metaphor to foreshadow the upcoming disgrace of this villainous character:
O, for the love of laughter, let him fetch his drum. He says he has a stratagem for ’t. When your Lordship sees the bottom of his success in 't, and to what metal this counterfeit lump of ore will be melted [...] your inclining cannot be removed. Here he comes.
This passage is full of repetitive “L” sounds. The shower of 'L' sounds in "love,” "laughter,” and "let" produce a flowing, musical effect. This alliteration gives the dialogue a playful and mocking tone, and the repetitive sounds give it a sense of movement and progressive flow. This echoes its content, as the First Lord is teasingly suggesting that Parolles will inevitably prove himself to be fake if they let him.
The scene also contains foreshadowing. By talking about what he expects to happen to Parolles if he’s allowed to “fetch his drum,” the First Lord hints at future events in the play. He sets up an expectation and excitement for the audience, as they can anticipate a funny and revealing scene is coming. Just as the First Lord suggests, Parolles does indeed reveal “the bottom of his character” shortly after this.
As if this weren’t enough, Shakespeare’s use of metaphor adds yet another layer of mockery to this setup for Parolles. When Parolles is referred to as a “counterfeit lump of ore,” the First Lord suggests that he is pretending to be something valuable but is in fact worthless. Just as heating ore reveals the true metal within, the audience is told that putting Parolles in a pressured situation will reveal his true character. The word “metal” here is also a pun, as it sounds like “mettle,” which is a period-specific phrase meaning "courage and fortitude." This usage is funny because these are the very qualities that Parolles lacks.
Near the end of “All’s Well That Ends Well,” Helen employs alliteration and metaphor as she reflects on the future and the relationship between actions and consequences:
When briers shall have leaves as well as thorns
And be as sweet as sharp. We must away.
Our wagon is prepared, and time revives us.
All’s well that ends well. Still the fine’s the crown.
Whate’er the course, the end is the renown.
In this passage Helen tells the audience that the “fine” is the “crown,” which operates as a metaphor in two ways. Firstly, she is implying that the results of other people’s actions can be both their reward and their punishment. The word “fine” holds a double meaning here, representing both “end” and “penalty.” She’s also implying that if everything turns out well, the way in which the objective was achieved is irrelevant. If the “end is the renown”—what is remembered—then the steps to get there don’t matter nearly as much.
Shakespeare uses alliteration, particularly the repetition of the "w" sound here, to evoke a sense of consistency and rhythm in the passage. The eponymous phrase "All's well that ends well" becomes especially poignant in this context. The “well” is the same in both places it appears, mirroring the point of Helen’s comment.
By referencing “briers” (blackberry bushes), Shakespeare invokes the sweetness of fruit and the sharpness of thorns. Picking blackberries means you might get scratched, but you do end up with blackberries. With this in mind, it becomes doubly clear from this passage that “all’s well that ends well” is just another way of saying “the ends justify the means.”