Let's forget the erroneous second power here. Mass is pretty simple to understand here. As for the acceleration, the force that stops the hammer during the impact is the same as the force that is inflicted upon the body per Newton's third law. The faster the mace is swung, the quicker the impact. This increases the inflicted momentary force, which can break bones if high enough. It is also good to remember that even faster maces have speed limit, as you can swing them only so fast. Thus, the length of the mace also becomes a factor. The velocity depends on the mass, size and shape of the mace, strength of the wielder and the skill of the user in some non-linear fashion.

As for CF, things are as coded. The helpfile does not mention the weight of the mace being a factor in boneshatter.