No Need to Guess the Plot
In all the nine kingdoms there is no place quite as safe and boring as the village of Ruthaven, no mythical creatures and no adventures to be had, the perfect place to hide a future king. [I'm not a stickler for sentences actually having to be sentences, but this being the first sentence, and the first impression, I'd go with: In all the nine kingdoms there is no place as safe and boring as the village of Ruthaven. With no mythical creatures and no adventures to be had, it's the perfect place to hide a future king.] Edmund Olivale has done his best to raise Lancel, the future king, alongside his daughter Kira, [Is Lancel Edmund's son? Stepson?] but when an assassin shows up at their front door the village is no longer a safe place.
Edmund flees with his family to the eastern mountains, searching for an old friend. With the head and wings of an eagle combined with the torso of a man and the arms, legs, and tail of a lion, Edmond’s friend is a beast of his own creation. ["His" meaning Edmund's friend or Edmund?] [Sounds like a griffin, although a griffin doesn't have a human torso. Then again, what difference does it make what kind of torso it is? If he were smart he'd have given it a torso of something less vulnerable, like a rhinoceros or a dump truck.] Now Kira knows why her father taught her the beast language of Rarack. He’s a beast weaver and with a little practice, she can be one too.
[English to Rarack Translator
Human : Rarack
Lioness : Rarack
Weapon : Rarack
Villager : Rarack
Covfefe : Rarack
Typical Beast Conversation
Beast 1: Rarack rarack!
Beast 2: Rarack rarack rarack!
Beast 1: Rarack.]
Kira will need her new ability to help her brother earn his rightful place on the throne of Vanderhelm. The creatures she creates become increasingly valuable [vital?] when the children are separated from their father. [What role are the beasts playing? Scouts? Guides? Bodyguards?] With little knowledge of the nine kingdoms, they place their faith in a well-traveled fifteen-year-old boy named Varro to guide them from kingdom to kingdom as they try to build an army.
To win support they must embark on quests like defeating an army of vengeful battle-toads, gathering ingredients to cure a paralyzed king, and recovering a flightless groundhawk that serves as a kingdom’s mascot. Soon the three kids find themselves with an army of followers, but how can they best assassins that seem to pop out of every corner and how can they ever beat the warlock king who can turn himself into the most fearsome beast imaginable, a three-headed dragon? [They have no chance of success. The good news is you won't have to write a sequel.]
Beast Weaver is a middle-grade fantasy novel, clocking in at 60,000 words. [I haven't seen "clocking in at" used for anything other than time. "Coming in at" might be better, although you could say Beast Weaver is a 60,000-word middle-grade fantasy novel.] I chose you as a literary agent [I'm writing to you] because you have represented M.G. fantasy before. Thank you for your time and consideration.
Unless there's a good reason for your future king's name to be so similar to Lancelot, change it.
Why is Edmund's son the future king? Who is the current king? Why and from whom did Lancel have to be hidden, and how come he's now free to travel everywhere recruiting an army instead of finding another hiding place? What enemy is Lancel's army going to fight, and why?
If you've got two beast weavers in your family, wouldn't it be better to create an army of beasts instead of recruiting a bunch of puny unreliable humans?
Why would soldiers be willing to join an army led by kids, and if they are willing to do so, why weren't they willing a few weeks ago? Just because the kids rescued their mascot and stomped on some toads?
I think you need to rewrite the query in a way that answers some of my questions and doesn't inspire me to ask so many other ones.
It might help to focus the query on one character.
Even when I offer Guess the Plot, they're all written by me and the same two or three other people. Maybe no one comes to this blog anymore?