Okay, assassins are such a fun niche, but 'skilled with unique fighting styles' makes me think beyond just 'good with a knife'. For the truly unique, I'd go with R.F. Kuang's 'The Poppy War'. Rin isn't an assassin in the traditional cloak-and-dagger sense, but she's a weapon of mass destruction trained in a brutal, shamanic martial art. Her power comes from channeling the Phoenix god, and the fighting is less about finesse and more about raw, apocalyptic rage. It's a style with a horrific cost, both physically and mentally.
Then there's the 'Nevernight Chronicle' by Jay Kristoff. Mia Corvere's shadow-walking is her signature. She can blend into and travel through shadows, which makes her approach to assassination incredibly cinematic and stealth-based. It's less about a flashy weapon form and more about using the environment itself as her primary tool. The fighting is dirty, practical, and often described with a visceral, almost gleeful brutality that fits the dark academy vibe.
For something older and more technique-focused, I still love the 'Night Angel' trilogy. Kylar Stern's 'Talent' is a magical ability that enhances speed, healing, and the ability to absorb skills, but the core is his wetboy training—assassination elevated to an art. The fighting is a mix of arcane magic, alchemical gadgets, and brutal close-quarters combat. It feels grounded in a dirty, street-level reality despite the magic system.