This is a book I read earlier this year. I wanted to write a review at the time but never got around to it. Overall, I'd say this was a very strong debut for Stavely. The plot had good bits of action and mystery. The characters were likeable. Stavely only scratched the surface of his world, but I saw a lot of potential there. While I can't point to any one thing that was phenomenal in this book, the sum total of all its elements was a very enjoyable read.
This book is primarily from the perspectives of the children of an assassinated emperor. We have Valyn, who is training with an elite group of soldiers. His plot features some good action and a lot of mystery. We also have Kaden, who is the heir to the throne. He is training with a group of monks in a remote location. I won't spoil the reasons for his training, though. That's a revelation in the book. His plot is a bit slower at first, but it's also got a good amount of action and mystery.
Of the three children, Adare, the daughter, gets the least page time. However, her story is very interesting in its own right, and I'd expect we'll see more of her in the coming books. Don't take this lack of focus on her to mean there aren't good female characters in this book. There are actually quite a few, especially in Valyn's plot line. They just aren't POV characters.
Now, the Goodreads description of the book says it's for fans of George RR Martin and Douglas Hulick, which seems an odd suggestion because I wouldn't compare this book to either of them. It's difficult for me to pin down to whom exactly it does compare. Sure, there are some echoes of Martin's influence, but it's really nothing like A Game of Thrones. A closer comparison might be Daniel Abraham (though The Emperor's Blades is faster-paced than much of Abraham's work). The biggest reason I can't compare it to Martin is the characters. Stavely's characters are more along the lines of Brandon Sanderson characters. Your heroes are generally good people.
Who knows? Maybe I should just stop trying to compare it. This book stands well on its own. It uses a lot of familiar fantasy elements, but the combination of them feels entirely original.