You have to be in Evie's skill tree (not Jacob's). If you are currently Jacob, then at the Main Menu click the
to switch to Evie. Then select the Skills menu.
There are 19 Stealth skills. They are listed here with their level restriction and skill point cost. A total of 38 skill points is needed to learn all the skills below. You get 1 skill point for every 1000 XP you earn during gameplay.
Level 1 - automatic
Whistle
Knockout
Stealth Navigation
Air Assassination
Level 2 - require 1 skill point each
Lockpicking I
Kidnap
Loot Takedown
Double Assassination
Level 3 - require 2 skill points each
Lockpicking II
Intimidation
Stealth I
First Strike I
Assassin Steps
Knife Master I
Stealth II
Level 5 - require 4 skill points each
Knife Master II (only Evie can learn this skill)
Stealth III (only Evie can learn this skill)
Level 6 - require 6 skill points each
Chameleon (only Evie can learn this skill)
First Strike II