Feat: Athamaru Weapon Familiarity

You wield weapons designed to work underwater with ease. You have familiarity with weapons with the athamaru trait and with crossbows, heavy crossbows, longspears, spears, and tridents—for the purposes of proficiency, you treat any of these that are martial weapons as simple weapons.

At 5th level, whenever you get a critical hit with one of these weapons, you get its critical specialization effect.