Readers Digest answer:

Look at the angle of the blades on a 2-blade rage with respect to the surface to be cut. The steeper (closer to 90 degrees) that angle gets, the more a blade will 'push' its way through rather than slice.

A more obtuse angle, such as a longer head like your hammerheads, offers more of a slice rather than a push.

You wouldn't try and cut a steak by pushing your knife down on it.... you slice it along the blade.