The motor is likely an induction type, which by design, "slips." So the more load placed on it, the slower it will spin. Which means, if you increase the blade pitch angle, this will produce more load for the motor, resulting in lower RPM, and probably a very similar amount of airflow overall. Of course, if you could install a more powerful motor, more air would flow.
One interesting thing about page 10 of that link. If you were to essentially put the motor on a dynamometer and produce a curve of it's torque vs. RPM, then you could calculate at what RPM the maximum power is produced, and adjust the blade shape, size, and pitch to suit. But if the engineer that designed the fan already did this, any improvement would be minor. And loading a small motor too heavily will cause it to reach a higher temperature and likely fail sooner. There is only so much power available from this motor to move air, and no "weird trick" will make it produce remarkably more airflow. Yes, you could "airfoil" the leading edges, plane-down the trailing edges, notch it, add "tips" or all sorts of other things, but these will not produce any remarkable difference as the motor is the limiting factor.
As a practical solution, could a second fan be added? Or this fan upgraded to a more powerful model? A squirrel-cage fan moves lots more air (and use a lot more power), but that topology doesn't lend itself well to ceiling use.