Nioh

The maximum proficiency score is 999,999. Your proficiency increases every time you hurt an enemy. Even if your weapon’s familiarity is at maximum (e.g. 900/900), it will keep counting additional proficiency points in the background. So you do not have to switch weapons after one is maxed out. If you stick to a single weapon type, you should unlock this at about 50% campaign completion. Just stick to one weapon type and it’ll come automatically in your playthrough.

You can see your proficiency for each weapon type in the additional stats. While on the player stats press to view additional stats for proficiency. Some weapons and accessories provide bonuses on proficiency so you can max them out quicker.

The fastest way to farm proficiency is in New Game+. Missions will now have a higher level and drop divine items (legendary gear). This makes leveling weapon proficiency a lot faster. Higher level enemies give a significant boost in proficiency. The mission level works as a multiplier, so pick a very high level mission. A good place to farm is the first main mission “Isle of Demons” (level 180 in New Game+). Either farm the normal mobs or keep replaying the Onryoki boss, but let him kill you before his health reaches zero.

Note: With the addition of Way of the Demon with Patch 1.08, enemies in these missions are stronger and higher level, granting faster weapon proficiency. This will speed up the proficiency grinding.