When making a weapon tier 4 it must be tier 3 and the creator must level 18. The process consumes 50 focus / resource and 1000 gold over 36d12 hours.
This unlocks slot 4 features and can be repeated multiple times.
Features with the (Exotic) can now be slotted. These slot features take up 2 tier 4 slots. While an exotic feature is slotted weapons require attunement and only 1 exotic feature can be slotted at a time.
(Exotic) The Slav: On a long rest, this weapon can be changed into any other martial weapon. It can also be re-slotted with 4 slots every long rest.
(Firearm)(Exotic) The Hard Roller: Gain final round, luck in the chamber, and para-causal rounds. This is hawkmoon d1 and d2.
Para-causal rounds: For every shot landed this weapon gains +1 to hit and damage on the final round. This feature resets when reloading.
(Firearm)(Exotic) Tex Mechanica: Increase the critical range by 1 and when killing a target gain 10 ft. range and +10 damage on attacks for 1 minute. These weapons also ignore the loading property and can be drawn instantly. This is for chaperone, last word, and dead man's tale type of weapons.