The way this Build works is that you'll use Unseen Form and the Black Knife Set to sneak up on enemies getting easy backstabs and attacks. These two things will muffle your sound and make you harder to see.

You can use Greatblade Phalanx when you know enemies are going to come at you, and cast Freezing Mist on tough enemies and Bosses to soften up their defenses via the Frostbite status effect.

Cast Founding Rain of Stars at the beginning of Boss fights when they start to come at you, and try to fight around the AoE it creates for best results. Try to dodge and use Double Slash while they are still in the AoE of FRoS.

Loretta's Greatbow is useful for situations where you need some long range or things will be markedly more difficult, and you can use Carian Retaliation to parry projectiles, which is great.

Scholar's Armament is your buff to really boost your damage over the top of a magic infused or cold infused Nagakiba. By keeping it Keen and using Scholar's Armament you will have higher damage potential as long as it remanis buffed.