I think knight in its current state dies too early, since both of his abilities can kill him, and while I think this is fine if you are using his abilities recklessly, I think knight could be more fun to play if it rewarded players for using playing more carefully. My suggestion is to give him the following passive:
Passive: Honor
You start the game with this passive disabled. If you kill an evil player with cold steel, you will become immune to death and you cannot be occupied when using cold steel. If someone attacks you you will lose this passive.
(Only cult/unseen players count, killing neutrals won’t activate this effect. You will also be immune to death if someone attacks a player you are guarding, but you will lose this passive as well. Trying to cold steel a member of the blue dragon will still kill you immediately even if you have this passive. If you lose this passive, you can activate it again by killing another evil role with cold steel).
This gives knights a reason to be careful with their abilities, and rewards them for using cold steel on the right targets.