You have to be in Jacob's skill tree (not Evie's). If you are currently Evie, then at the Main Menu click the
to switch to Jacob. Then select the Skills menu.
There are 18 combat (Fight) skills. They are listed here with their level restriction and skill point cost. A total of 35 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
Multi-Finisher
Stun Attack
Counter
Tool Combo
Level 2 - require 1 skill point each
Health Boost I
Unstoppable I
Slayer I
Level 3 - require 2 skill points each
Health Boost II
Unstoppable II
Counter Boost
Health Boost III
Execute I
Slayer II
Mutilate I
Level 5 - require 4 skill points each
Adrenaline
Execute II
Mutilate II (only Jacob can learn this skill)
Level 6 - requires 6 skill points
Combat Stamina
from gosunoob.com