Derrick Flynn should be dead, but he’s up and running instead. He’s just survived his second chance encounter with the infamous killer Splitlip, a man assumed dead for decades. I think your hook is actually the second sentence, and I would consider striking the first. Splitlip is a great name for a villian, and the fact that it's Derrick's second encounter is intriguing. Also, cutting the first line will eliminate the echo (word repetition) of "dead."

Several years ago, Splitlip killed Derrick’s dream of developing his magic abilities when he murdered his mentor. This is first mention of magic, or indication that this is anything other than a contemporary thriller. Get the presence of magic into your opening para. Also, why can't Derrick just get a new mentor? Derrick’s superiors chalked the death up to a botched spell--untested sorcerers become erratic and delusional when they can’t control their magic--and expelled him from their group. Okay, so it's not so much that the mentor died that Derrick can't develop his abilities, it's that he was blamed for the death and banned. Again, I think you're giving information in a backwards fashion. It was a bitter pill to swallow, made worse by the fact that even his elder brother Alek, a sorcerer himself, didn’t believe him either. Believe him about what?

Now, those woes and doubts dissolve in adrenaline and glorious affirmation as Derrick runs from his would-be grave. Splitlip’s reappearance means redemption--if he can catch or kill him. It’s a chance he won’t let pass; but it’s one he can’t take alone. Definitely confusing. Somehow Splitlip still being alive is evidence that Derrick was not at fault for his mentor's death... but I have no idea what the connection is.

Alek agrees immediately when Derrick requests help, even though he hasn’t taken a bounty in years. How does a bounty come into this? Eager for his acceptance, Derrick sees this quick consent as the first step to regaining Alek’s trust, and perhaps even earning his esteem.

Only when they’re miles away from home does Derrick learn Alek’s true reason for wanting to help--to resurrect his late fiancee Cecily--and it threatens more than his shot at redemption. So... Alex actually just wants to find Splitlip so he can help resurrect his dead g/f? How does that threaten Derrick's goals directly?

CECILY'S KNOT (fantasy, 130k words) Holy word count. That's high. Even for a fantasy realm. As a debut trying to break into a very competitive marekt, you'll need to get that lower. Ideally under 100k may appeal to readers who enjoy Tad Williams' rich worlds and Patrick Rothfuss' mellifluous style. This debut novel is written as the first of a four part series, but could be adapted into a standalone story. You definitely need to push this as a standalone with series potential, rather than the other way around.

Your story sounds quite cool, and I like the concept, but your query is suffering from too much assumed knowledge. You'll see above that most of my critique revolves around needing clarification, or not knowing enough in order to draw the right conclusions. Get more explanatory info in there; we don't know this story. You do. It's possible to answer my questions and keep this concise.