The primary purpose of the Carmonized hammer (i.e. cut down to minimal dimensions that reduce the curb weight of the hammer by about 50 percent) is to allow the hammer to run at a significantly higher velocity when it falls, decreasing lock-time and imparting that "fast slap" on the primer that is most efficient for ignition. As I have mentioned here previously, I got the idea from an old photo of a PPC revolver done by a west-coast gunsmith back in the '70s. As indicated above, with a Carmonized hammer you can lighten up the spring tensions noticeably, and yet still maintain full ignition reliability.
The secondary benefit of Carmonizing the hammer is that it reduces the jarring and jostling upon impact when the hammer falls, which may improve inherent accuracy and definitely creates a tangible and noticeable improvement in feel. Here's an interesting visual depiction of this effect:
Lightening the hammer works with both types of hammers--those designed for the frame-mounted firing pin, and the older style with the hammer nose.