Definitely a rework.

Bonus Proficiencies

When you choose this archetype at 3rd level, you gain proficiency with the disguise kit and the poisoner’s kit. When you use your disguise kit, you can choose to spend 25 gp and 3 days, creating a false identity for yourself. You can’t establish an identity that belongs to someone else. For example, you might acquire appropriate clothing, letters of introduction, and official-looking certification to establish yourself as a member of a trading house from a remote city so you can insinuate yourself into the company of other wealthy merchants.
Thereafter, if you adopt the new identity as a disguise, other creatures believe you to be that person until given an obvious reason not to.

Assassinate

Starting at 3rd level, you are at your deadliest when you get the drop on your enemies. You have advantage on attack rolls against any creature that hasn’t taken a turn in the combat yet, In addition, any hit you score against a creature who hasn’t taken their turn in the initiative is surprised. When a creature is hit with a surprise attack it counts as a critical hit.

Astonishing Strike

Starting at 9th level, When you use your cunning action to use the hide action, you can gain your assassinate feature against creatures you have hidden from and can treat them as surprised.

Quick Maneuvering

Starting at 9th level, when you roll your initiative you can add your Proficiency bonus to your initiative roll.

Infiltrator

At 13th level, you gain the ability to unerringly mimic another person’s speech, writing, and behavior. You must spend at least an hour studying these three components of the person’s behavior, listening to speech, examining handwriting, and observing mannerisms. Your ruse is indiscernible to the casual observer. If a wary creature suspects something is amiss, you have advantage on any checks you make to avoid detection and they have disadvantage on checks to uncover you.

Expert Killer

At 13th level, the poison that you produce from your mixtures affects creatures with resistance, and treat immunity as resistance, when you are trying to gather, materials for your poisoner’s kit, using skills such as Nature, Sleight of Hand, or Survival, you can double your proficiency bonus if you don’t already have expertise and gain expertise in your disguise kit and poisoner's kit.

Death Strike

Starting at 17th level, you become a master of instant death. When you attack and hit a creature that is surprised, it must make a Constitution saving throw (DC 8 + your Dexterity modifier + your proficiency bonus). On a failed save, double the damage of your attack against the creature.