Multi-class characters obtain all of the weapon proficiencies for all of their classes – both the starting proficiencies and the proficiencies gained by leveling up.

Dual-class characters gain all the starter weapon proficiencies for their new class, and then gain weapon proficiencies at the regular rate for that class. Any time they level up, dual-class characters must pick a proficiency for a weapon that is usable by the class they just gained a level in.

There are no core rules for retraining weapon proficiencies.

As a rules extension, a weapon proficiency can be exchanged for another in 1 month at the cost of a cumulative 250 gp times the highest class level of the level of the character (1st = 250, 2nd = 750, 3rd = 1500, 4th = 2500, etc.).^Ex As with regular training, the character cannot perform any other activity during this time; if they do, all progress and expense is lost.