Weapon Mastery
Your training with weapons allows you to use the mastery properties of two kinds of Simple or Martial Melee weapons of your choice. Whenever you finish a Long Rest, you can practice weapon drills and change one of those weapon choices.
When you reach certain Barbarian or Fighter levels, you gain the ability to use the mastery properties of more kinds of weapons, as shown in the Weapon Mastery column of the Barbarian Features and Fighter Features tables.
This feature for the Fighter class starts with three weapon masteries instead of two.
This feature for the Paladin, Ranger, and Rogue classes is limited to only weapons with which you have proficiency.