Weapon Proficiency

Proficiency with a weapon allows you to add your proficiency bonus to the attack roll for any attack you make with that weapon. If you make an attack roll using a weapon with which you lack proficiency, you do not add your proficiency bonus to the attack roll.

Weapon Proficiency

overview
Train one hour per day with a weapon in a Practice Yard equipped with combat dummies or an archery range with a weapon.
On a successful Mastery roll, you gain the proficiency permanently at a cost of one Proficiency Slot, and this training regimen slot becomes open again. Your mastery check can be made using Dexterity if you are training with a ranged or finesse weapon.

linked to ability score
Str

training duration Permanent

Classes and Weapon Proficiencies

Your class can grant you proficiency with certain weapons or categories of weapons. The two categories are Simple weapons and Martial weapons.
Most classes can use simple weapons with proficiency. These weapons include clubs, maces, and other weapons often found in the hands of commoners.
Martial weapons, including swords, axes, and polearms, require more specialized training to use effectively. Most warriors use martial weapons because these weapons put their fighting style and training to best use.

Creature Weapon Proficiencies

Assume that a creature is proficient with its weapons. If you swap them out, you decide whether the creature is proficient with its new equipment.
For example, a Hill Giant typically wears Hide armor and wields a Greatclub. You could equip a hill giant with Chain mail and a Greataxe instead, and assume the giant is proficient with both, one or the other, or neither.