Blade Dancer

The creature's eyes pierce the gloom, but its enemy's movements are too quick. It is alone and defenseless, slow to react against such a practiced hand.  A shadowy figure darts across the wall of the dimly lit passage. Three daggers leap out of the darkness striking its vitals, and the creature knows no more.

Precision

Starting at 3rd level, you master the art of thrown weapons. When attacking with a weapon with the light and thrown properties you have +1 to your attack rolls and you apply your damage modifier to your offhand attacks. In addition, as part of your attack with a light thrown weapon you may draw a weapon of that type.

Guile

When you choose this archetype at 3rd level, you gain an acute awareness of your foes. You have advantage on initiative rolls.

You also gain an additional way to Sneak Attack.  You don't need advantage on the attack roll to use your Sneak Attack against a creature if you are  outside of its reach and you don't have disadvantage on the attack roll. All the other rules for Sneak Attack still apply to you.

Surestride

Starting at 9th level, you are always able to keep your footing. You ignore difficult terrain penalties and your base speed increases by 10 feet.

In addition, you may stand up from prone with no movement penalty.

Parkour

Starting at the 13th level, you can execute maneuvers of profound agility. You gain expertise in acrobatics and can move at full speed on vertical surfaces. If you reverse the direction of your move or end your turn on a vertical surface you fall. 

In addition, when you make a running jump, you may use dexterity instead of strength.

Lightning Reflexes

When you reach 17th level, you can throw with unmatched speed and subtlety. When you take the attack action with a weapon with the light and thrown properties, you can make one additional attack with the same weapon type. This additional attack can apply Sneak Attack damage, but not against the same target.