Heroes can use any equipment they like; however, each class has a list of weapons and armor types they are most skilled with. Weapons used without proficiency cannot crit. Defending while wearing armor without proficiency costs 1 additional action.
Equipment Proficiency
Core Rules v2 p. 33
Related Rules
4Armor & DefenseCharacters & Equipment / Equipment & Currency
Custom Weapon DiceCharacters & Equipment / Weapons
Customizing WeaponsCharacters & Equipment / Weapons
Weapon PropertiesCharacters & Equipment / Weapons