Oath of Silence

Contrary to popular belief, those who swear an oath of silence are not mute and are not hesitant to use their voice. They see the corruption inherent in all levels of society, from the aristocracy, the churches to the criminal underworld. Masters of weeding out deceit and lies those who have sworn the oath stand as a bulwark of truth and keepers of powerful secrets. The rallying power of music and the bards that conjure it, politicians and nobles weaving intricate webs of falsehoods to keep the people in line, generals spreading rumors among their own forces to demonise their foe, priests twisting the gospels of their gods for their own gain, criminals lying and scheming at the cost of others, devils who seduce mortal to offer up their souls for power. All of these are dangerous in the eyes of a paladin of silence and a reason to fight and adventure. Another path many paladins of silence take is to safeguard the world against powerful secret, their mind a vault of various secrets, blackmail material, forbidden lore and lost magic. 
The paladins of silence are not part of an order and mostly act independently after the order of silence was destroyed by worshippers of Vecna, the god of secrets. This caused many of the older members who still remember the grand halls of the Temple of Candour to harbor great resentment against the god of secrets and seek to discover the secrets to his destruction.

Tenents of Silence:

• Truth above all: Those who would attempt to lie and cheat you are never to be trusted.
• Power of the truth: A single secret is as powerful as a thousand swords.
• Above the law: You will not let any authority force your hand to act against your judgement.

Fortfied Mind

When you take the oath of silence at 3rd level you become a beacon for truth and keeper of secrets. You learn to weed out the lies being told to you while fortifying your mind against anyone who would try to pry you for information.
You gain Expertise in Insight and proficiency in persuasion if you did not already.
Additionally you have advantage on saving throws against Divination spells and anyone attempting to read your mind must first succeed a Wisdom saving throw against your paladin spell save DC or be blocked from your mind for the next 24 hours.

Channel Divinity

When you take this oath at 3rd level you gain the following 2 Channel Divinity options.

• Sensory Restraint. You can use your Channel Divinity to shut down the senses of your foes. As an action you can target a creature within 30 feet of you, causing them to hear a high pitched sound inside their mind. The target must succeed on a Wisdom saving throw of be silenced and deafened for 1 minute. The target cannot talk nor cast any spells that require vocal components. This also stops them from being able to speak telepathically.
  
  
• Force Truth. You can use your Channel Divinity to force out the truth out of a creature whether they want to or not. As an action you can target a creature within 30 feet of you, forcing them to make a Wisdom saving throw. On a fail the creature becomes unable to lie or avoid answering your questions. This affect lasts for 1 minute, the creature repeats the save and the end of it's turn.

Aura of Stubborness

At 7th level you and any friendly creatures within 10 feet of you gains advantage against being put to sleep by magical means or being silenced, deafened or blinded.

At 18th level the range is increased to 30 feet

Vault of Secrets

At 15th level your mind is fortified against intrusion. Anyone attempting to read or enter your mind will find it filled with a still deafening silence, the intruder must also make a Wisdom saving throw or take psychic damage equal to your level and be expelled from your mind.
Additionally you gain a flawless memory and cannot forget any information unless by magical means such as the Modify Memory spell.

Scrutinous Glare of Judgement

At 20th level, you are able to dig through your for knowledge of your enemy and peer into their small hidden weaknesses, making sure each strike counts. You can choose a target that you can see within 60 feet of you. You narrow your focus, learning any resistances, immunities or vulnerabilities the target might have and all of your single target attacks deal maximum damage to the target.

This effect lasts for 1 minute or if the target reaches 0 hit points and can be done a number of times equal to your Charisma modifier, if you have no uses left you can use a Channel Divinity to use this ability.