I'm a bit confused with how archetypes can stack together. For the purpose of what I'm wanting to do, can I combine the Two-Weapon Fighter and Tactician archetypes to replace Bravery with Tactical Awareness?
No, Archetypes are "all or nothing" things. YOu take the entire archetype or you don't, you can't just pick one ability from it and take that.
And no you can't combine those two, since Tactician modifies Weapon Training 1 and Armor training 3, and Two weapon fighter modifies those also.
Okay, thanks!
If two archetypes replace the same base class feature, you cannot combine them.
So, if the base class has features A, B, C, and D, and both archetypes replace feature B, you can't combine them.