What does the Exotic Weapon Master’s Uncanny Blow require?

The Exotic Weapon Master (Complete Warrior, p. 30) has, as one of its optional class abilities, the Weapon Stunt Uncanny Blow.

Uncanny Blow gives a benefit to the Exotic Weapon Master "[w]hen wielding a one-handed exotic melee weapon in two hands[.]"

To trigger this benefit, must a creature wield a one-handed exotic weapon that does not offer a two-handed martial option?

Would an Exotic Weapon Master without Exotic Weapon Proficiency: bastard sword still be able to benefit from this weapon stunt? The weapon stunts themselves only require Weapon Focus – and since the Bastard Sword is also a two-handed martial weapon, a character proficient with martial weapons could presumably take Weapon Focus in the bastard sword, always intending to use it in two hands. That character still has Exotic Weapon Proficiency with the Spiked Chain, and so the character does fulfill all the requirements for the class and the stunts.

But, if the character always plans on using it as a martial weapon in two hands, then it is never being used as an exotic weapon (ignoring that putting two hands on such a one-handed exotic might make it non-exotic anyway) . . . So can the Exotic Weapon Master ever benefit from Uncanny Blow with a bastard sword?