In Hyadian Schism, there is no penalty to using a weapon without a Weapon Proficiency. This is strictly a bonus you get for being trained in that specific weapon type. This is always based on a particular type of weapon. If you have Proficiency in using a Kopesh, you don't get the Proficiency Bonus in other sword types.
Proficiency can be stacked:
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(weapon type) Proficiency - Cost: One Weapon Proficiency Slot.
(weapon type) Expert - Cost: Two Weapon Proficiency Slots.
(weapon type) Master - Cost: Three Weapon Proficiency Slots.
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Basic Proficiency: +1 to hit & parry with the weapon
* Attacks that exceed your parry, for quality rating reduction purposes are reduced by three when referencing chart.
* May not quick draw or sheathe a weapon unless you have a class ability which overrides this.
Expert Proficiency: additional +1 to hit & parry with the weapon
* Attacks that exceed your parry, for quality rating reduction purposes are reduced by five when referencing chart.
* May not quick draw or sheathe a weapon unless you have a class ability which overrides this.
Master Proficiency: additional +1 to hit & parry with the weapon. Lowers critical hit needed number by one.
(Example: If you normally need a Natural 20 to get a critical hit, you now do critical hits with a Natural 19.) Also unlocks special maneuvers for that weapon if available.
* Attacks that exceed your parry, for quality rating reduction purposes are reduced by ten when referencing chart.
* You can quick draw or sheathe a weapon as a free action.