When you are talking about Weapon Proficiency, Each weapon has its own proficiency in a certain level that you can simply go up by playing our TDS.

And please be reminded that it does not work when you are in offline mode.

At a certain level of proficiency in a weapon, each one has a rune socket that could be unlocked and improve skills with buff.

These buffs are passive and used at all times while in a dungeon, stage, and so on. To get all the runes, you need to maximize the proficiency level up to 30.

* Weapon proficiency will be increased based on the number of monsters you kill in stage, dungeon, etc