Merfolk Weapon Familiarity

You were taught the most effective weapons of the sea. You gain access to all uncommon weapons with the merfolk trait. You have familiarity 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 and any that are advanced weapons as martial weapons.

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