Raven's Shadow

There are many who would take up the paladin's vow in order to smite evil. But as they march off to war clad in holy plate armor, there are those with the same goal in mind that stalk the shadows around them. Armed with stealth and all the radiant power given to their armor compatriots, they act as holy assassins, shining blades in the dark that strike quickly and leave behind only a smoldering pile of smitten undead and demons. 

Eyes In The Dark

Starting at 3rd level, when you choose the archetype, the darkness becomes no obstacle to you but every bit as one to your enemies. You can see normally in darkness, both magical and non-magical, to a distance of 120 feet. additionally, while in darkness, you are invisible to any creature that relies on dark vision to see you in the darkvision.

Smiting Edge

Starting at 3rd level, when you deal sneak attack to a creature, you can choose to have that damage be dealt as radiant damage.
You also dont need advantage on the attack roll to use your sneak attack against a fiend or undead creature. when you deal radiant damage to a fiend or undead in this way, you roll d8's instead of d6's with that sneak attack.

Without Fear.

Starting at 9th level, you can no longer feel any fear and as such, you can no longer be frightened.

Uneering Stalker

Starting at 13th level, you attain the gifts neccessary to stalk evil into its darkest of dens. You can cast detect good and evil at will.
additionally, anytime you deal radiant damage with your sneak attack, any fiend, abberation or undead of a CR equal to your proficency bonus or less is reduced to zero hit points.

Banishing Backstab

At 17th level, when you deal sneak attack to a creature, you can force them to make a charisma saving throw with a DC of 8 + your charisma modifier + your proficency modifier. on a failed save they are banished to a small demi-plane for one minute. You must concencrate on this banishment as you would a spell and you can only have one creature banished at a time.
This effect does not work on creatures with legendary actions or resistances.