Proficiency is a Stat in Nioh.
Proficiency is the measure of your effectiveness with a specific category of Weapons. Using them effectively in battle improves your Proficiency which in turn earns you Samurai Skill Points to spend on Skills. Proficiency is maxed out at 999999. As you increase Proficiency you will also unlock certain Master Missions.
The following lists the amount of proficiency points for a single weapon at which you will acquire a Samurai Skill Point:
You do not get any additional Samurai Skill Points for proficiency beyond 300,000.