The way to become a knight is to spend 40% or more in either the vitality stat or the weapons stat. This allows for a few different variations of knights to lean more on the weapon or hp side of things, but fundamentally this is what must be invested in to become a knight.
Parent classes
The knight is a hybrid class of the warden and the warrior
Overview of the class
The knight class allows for versatile weapon combat and survivability with increased health and regeneration. upon awakening #1, knights will gain a weapon aura which boosts the size of weapon particle effects as well as add extra features to the weapon. awakening #2 will be an omniboost like most builds, and grant a 10% damage reduction.
Conclusion
The most underrated and least hyped class, knights are hidden gems that have much potential and allow for combat with weapons while being able to survive hits and regenerate HP easier. Rumor has it that knights may also grant access to spirit weapony similar to wardens though this is yet to be confirmed. (or it already has been and I just am not aware of this)