Powerful Weapon Wielder

You have trained with one, specific two-handed weapon until you are able to wield it one handed:

• You may treat this one weapon as versatile, able to be used by your character either one-handed or two-handed; 
• When wielded one-handed, the weapon does one die worth lower damage
  (i.e. A greataxe normally does 1d12 damage;  wielded one-handed it would do 1d10;  A greatsword normally does 2d6 damage.  Wielded one-handed it will do 1d6 + 1d4)
• This feat may not be applied to polearms.