I started playing an unarmed fighter, not the archetype but rather fighting with fists and going regular fighter (due to lack of other options I might like) for armor training (full plate in full speed) and weapon training and the advanced versions of such, for Hell's Rebels AP.
To make the most of the admittedly not ideal weapon of unarmed attack for a fighter, I was hoping to pick up Advanced Weapon Training feat around level 5 or so and pick up Warrior's Spirit to help boost damage/options.
However I'm currently uncertain about application.
Warrior Spirit (Su): The fighter can forge a spiritual bond with a weapon that belongs to the associated weapon group, allowing him to unlock the weapon's potential. Each day, he designates one such weapon and gains a number of points of spiritual energy equal to 1 + his weapon training bonus. While wielding this weapon, he can spend 1 point of spiritual energy to grant the weapon an enhancement bonus equal to his weapon training bonus. Enhancement bonuses gained by this advanced weapon training option stack with those of the weapon, to a maximum of +5. The fighter can also imbue the weapon with any one weapon special ability with an equivalent enhancement bonus less than or equal to his maximum bonus by reducing the granted enhancement bonus by the amount of the equivalent enhancement bonus. The item must have an enhancement bonus of at least +1 (from the item itself or from warrior spirit) to gain a weapon special ability. In either case, these bonuses last for 1 minute.
If I was to select unarmed strike under the Close Weapons group, would the enhancement bonus granted by Warrior Spirit apply to all my unarmed attacks (if say I were to TWF unarmed) like an amulet of mighty fists? Or would it just be to one unarmed striking limb, such as a fist, and I can full attack with it with high BAB, but any offhand unarmed strikes wouldn't benefit from Warrior Spirit?
If I were to use one the enhancement bonus to instead apply a weapon special ability, like bane or flaming, would an amulet of mighty fists +1 treat the weapon as a +1 so I can apply the weapon special ability directly? Or would AoMF +1 not count as the enhancement bonus is granted from an external source (AoMF) and not "from the item [fist] itself" as stated to be needed by Warrior Spirit?
IUS is one weapon that you can two weapon fight with.
No idea how to rule the second one.
If your Unarmed Strike already gets a enchantment bonus from the Amulet you should be fine to add abilitys with Warrior Spirit.
As for TWF with Unarmed Strike, your whole body is the weapon, and your left hand and right hand are not seperate weapons, and you my TWF with it, so the enchantments should apply to both.