Medical Weapon Familiarity Feat 4

You know how to use the tools of your trade so well you're capable of using weapons with similar features to defend yourself. You gain access to all uncommon weapons with the injection trait and all uncommon weapons in the knife weapon group. For the purposes of proficiency, you treat any injection and knife weapons that are martial weapons as simple weapons and any that are advanced weapons as martial weapons. When wielding a simple weapon with the injection trait or in the knife group, you increase the damage die size of that weapon by one step.

At 5th level, whenever you get a critical hit with an injection weapon or a weapon in the knife group, you get its critical specialization effect.