Here are some custom proficiencies:
Formation Defense This is a weapon proficiency available to fighters. When at least two fighters with this proficiency fight side-by-side, they are able to better protect each other (AC bonus +1). Fighters can specialize in this for a total AC bonus of +2. The Sob-Rooz military devotes much training to this technique. The elite Ardan-Kryll units are typically specialized.
Mounted Defense This is a weapon proficiency available to fighters. With this proficiency, mounted fighters can designate who takes damage on a successful hit, the rider or the mount. This proficiency does not confer any AC modifiers to rider or mount. It simply allows the choice of who sustains the damage on a successful hit.