So with the help of a couple people on the Pathfinder/Starfinder Character Conversion group on Facebook, I've got a great idea for a Half-Swording stance. I'd love to hear what others think of it.
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Half-Sword Stance feat line:
Half-Sword Style [Combat, Style]
--Pre-Req: Weapon Training (Heavy Blades or Light Blades), Weapon Focus, Weapon Versatility
--Benefit: While in Half-Sword Stance Apply double your Weapon Training (Heavy Blades or Light Blades) bonus to Hit against people wearing heavier armor than you while wielding a weapon from one of the respective groups.
Half-Sword Mordhau [Combat]
--Pre-Req: Half-Sword Stance, Base Attack Bonus +6, Power Attack, Weapon Specialization, Combat Stamina
--Benefit: While in Half-Sword Stance you may perform a Mordhau strike with a weapon from the Heavy Blades or Light Blades weapon group. Resolve this as a Combat Maneuver. If successful, apply damage as if you struck them with the weapon but bludgeoning and they become dazed for 1 round. If you beat their CMD by 10 or more: Staggered instead. If you beat their CMD by 15 or more: Stunned Instead.
Half-Sword Coup De Grace [Combat]
--Pre-req: Half-Sword Stance, Half-Sword Mordhau, Improved Critical, Push the Limits
--Benefit: While in Half-Sword Stance and wielding a weapon from the Heavy Blades or Light Blades group: You may now deliver a Mordhau maneuver in place of an attack in a full attack action. If you successfully hit with your Mordhau you may spend 5 Stamina for your next attack resolved against them to be instead performed as a Combat Maneuver. If you succeed, immediately resolve a Coup De Grace against the target.
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As written, a Human Fighter would be able to achieve the third feat in this line by 8th level if they take nothing but prerequisites.