Here's a link to an article that explains the science behind pie dough.
How Alcohol Makes A Flakier Pie Crust: The "Proof" Is In The Pie - Scientific American Blog Network
It explains why Vash's vodka method makes the flakiest crust. You need moisture to bind the flour together, but water interacts with the glutens to make the crust harder. Alcohol doesn't react the same way as water, so you get the benefit of liquid binding the flour without water making things hard.