Level 2
You gain proficiency with light armor. If you are already proficient with light armor, you instead gain proficiency with heavy armor. If you are already proficient with heavy armor, you instead gain a fortification ability when wearing heavy armor or powered armor. Your fortification gives you a 20% chance that a critical hit is treated as a normal attack, dealing normal damage and not applying any critical effect. You roll your fortification percentage chance before the critical hit’s damage is rolled. If you have a fortification ability from another source (such as a force field), you instead increase the chance of a critical hit being created as a normal attack by 20% (to a maximum of 100%).
Source
Pact Worlds pg. 186