You have dedicated yourself to the mastery of a weapon, regardless of it's form.
Prerequisites: Martial Weapon Proficiency, Int 17, Knowledge(arcana) 15 Ranks
Benefit: When wielding a weapon with the Transformative or Greater Transformative magical weapon properties, you are proficient with the weapon regardless of what form it takes, even if it is an exotic weapon you would not normally be proficient in. Any feats you have that apply to a specific weapon type (example: Improved Critical, Weapon Focus) can be applied to the weapon regardless of form, unless that weapon type wouldn't qualify normally(You cannot apply the benefits of Dervish Dance to any weapon but a scimitar, you cannot apply the benefits of Tripping Staff to any weapon but a quarter staff, etc)
Furthermore, if you have the Weapon Training & Advanced Weapon Training or Sacred Weapon class features, you can apply their benefit to the weapon, regardless of what form it takes.