My thoughts are in blue, words to delete are in red, suggested rephrasing is in orange.

Ciel Briar’s sole dream is to escape her abusive mother. Great hook, thank you! A dream that gnaws at her insides due to the impossibility. However, this isn't a complete sentence so I'd combine the two and explain why it's an impossibilty. That is, until the charming Crown Prince of Eireann hosts a birthday celebration held solely You've got a couple of echoes here with sole/solely and holds/held An echo is when you use the same or similar words too closely together, and is best avoided. for the youthful faeries of the kingdom. The party is dazzling, but not more than the handsome stranger courting her. Mid-swoon, she discovers he's the Crown Prince's assassin, I feel like it's hard to discover anything while swooning and as the only one who can identify him, she becomes a valuable asset to the kingdom. Is she an asset or a threat? I don't understand why her knowing who the assassin is would be a big deal... unless I'm reading this wrong and he's not a court assassin, as in an employee, but rather he was actually sent to kill the Crown Prince. Which raises the question of whether he was succesful or not.

Welcomed into the safety of the castle walls, Ciel learns of the royal family’s esteemed bodyguards. The Watchers are the answer to escaping her wicked mother, How is her mother wicked? Why does she want to escape her? How are they the answer? but Ciel must prove herself worthy before the assassin is found or else return home. Worthy of what? The chances are slim for an untrained, weak faerie like her to become part of the elite guards. Why would she need to become part of the elite guard? Doesn't the fact that she can ID this guy make her important enough? Desperate, she finds the perfect opportunity when a starry-eyed woman approaches her, telling her of the assassin’s location. If Ciel can find him before the kingdom does, she will earn Watcher status, but the woman is a witch, and Ciel is ambushed. Forced into a magical bargain with the assassin, she's now a rebel spy. I don't understand why she wouldn't just tell the Watchers where he is... unless what you're trying to say is that her only chance of escaping her mother is by becoming a Watcher, and in order to do that, she's got to nab him herself. This all needs clarified.

The game she must play is tricky, and as Ciel learns the rules, she discovers her kingdom is more flawed than she imagined. With a rebellion on the rise, she must decide which side she wants to take: her beloved Crown Prince, or the cunning assassin tugging at her heart. This was the first time there's any mention of her having any sort of romantic feelings for either one of these fellows.

I saw that you represented [author name] with [book name], and I am excited to seek your representation for A KINGDOM OF STARFLOWERS AND BLOOD, a young adult fantasy romance complete at 100,000 words. An Irish folklore setting with themes of political intrigue, power, and resilience, it will appeal to fans of Witches of Ash and Ruin by E. Latimer and Powerless by Lauren Roberts. Good comp titles. The YA fantasy market is absolutely flooded right now, and breaking in will be difficult. If you can get your word count under 100k, that might help.

Last year, I won the Kingsmead Book Fair Young Writers’ Competition for the young adult age category, a national writing competition in South Africa. Currently, I intern at Future House Publishers. Great bio!

Overall, there are quite a few instances here where you know what you're trying to convey, so it reads correctly to you, but the reader doesn't have the background knowledge, so it's confusing. Clarify that the assassin is an enemy, not in the Prince's employ (that's how I first read it). Explain why her mother is so horrible and why escaping her is impossible, and clarify why becoming a Watcher herseelf is the only way out. Also, you say she swooned but that's the only indication that she's got eyes for either one of the male characters, and if a romance / love triangle is a part of this, that will need to be included, as well as some nod to the role each of these guys will play - is the Prince a nice guy, who doesn't want power? Is the assassin a lone wolf who doesn't want to fall for her, either? Just one line for each of the fellows will give us some feel for them as characters.