Rogues who have mastered the art of the Crowdblade become masters of blending in with a crowd. They do so by becoming that which no one else pays attention to: a faceless nobody. Aiding in this is the ability to wield psionic energies. Oftentimes these take the form of deadly energy blades that require no hands. Those strongest in this art are able to take on the appearance and sound of others, allowing them to infiltrate as they please.
Source: I Made It the Fuck Up
Unimportant
At 3rd level, if both your head and face are obscured, you have advantage on Dexterity (Stealth) checks when at least two other humanoids are within 10 feet of you. If ten or more other humanoids are within 20 feet of you, you may add 10 to Dexterity (Stealth) checks you make.
While your vision is obscured, you may telepathically see through the eyes of any willing humanoid within 60 feet of you.
Psionic Blades
Also at 3rd level, the psychic energies you channel to become unremarkable can also be focused to manifest weaponry. As a bonus action you may create two daggers of psychic energy, which you can wield telepathically. These daggers function as wielding normal daggers would, but do not require free hands to use, and deal psychic damage instead of piercing.
Further, as these weapons prey on the expectations of your enemies, they become more potent if you are presenting yourself in an unthreatening manner. If both of your hands are free and you appear to be unarmed, the psionic daggers damage dice is upgraded from d4 to d6.
Starting at 13th level, the melee attack range of your psionic daggers is increased by 5 feet.
Background Piece
By 9th level, You have not only learned to disappear in a crowd, but also to become so unnoticeable that you can disappear into any object roughly equal to your size or larger. If you remain stationary for a minute near an object large enough to conceal you, such as a barrel, a crate, some foliage, or a haystack, you may make a Dexterity (Stealth) check with a +10 bonus to become hidden.
One of the Crowd
At 13th level, your enemies have a hard time discerning you from among your allies while in battle. As a reaction when you are hit by an attack and you are within 30 feet of two or more willing humanoids and have a willing humanoid within 5 feet of you, you may roll a d20. If you roll an 11 or higher, the attack instead hits a willing humanoid of your choosing within 5 feet of you.
A Familiar Face
Starting at 17th level, your ability to blend in as part of the crowd has helped you master the act of being anybody. If you observe a humanoid for one uninterrupted minute or more, you can psychically make people perceive you as them. You may cast Disguise Self to take on their visage, and perfectly replicate their voice for the duration of the spell via telepathy. Creatures have disadvantage on the saving throw to discern you if your appearance is false when using this feature.
You may use this ability a number of times equal to your Charisma modifier to a minimum of 1. You regain all spent uses when you complete a short or long rest.