For those of you who haven't studied rotational mechanics or don't get it. Moment of inertia is how difficult something is to accelerate not linearly but in a an arc around a central point. Rotational acceleration is not however the "acceleration" of the weapon but a measure radians per second per second.
So moment of inertia is how difficult it is to increase somethings angular velocity.
In practice the moment of inertia increases as the majority of mass moves further away from the point of reference.
I am proposing using a real physical relationship that we could improve the turnspeed code. Using inertia in place of length within the code with an appropriate scaling factor of course.
At the moment spears are more difficult to spin than a bardiche, wth? Not fair really so i propose a real world approach.
Moment of inertia for a thin rod rotating about its end plus a standard moment of inertia for the character would represent the swords and spears. Heavy ended pole-arms could get a higher moment of inertia per unit length maybe 1/2*ml^2. Mauls as above could be treated as a point mass with an even higher moment at ml^2. Keeping in mind that their length is much lower and that length is to the largest power in the inertia equation.
This will buff lighter weapons and their damage or speed might need to be bought into line accordingly.
The longer and heavier the more penalty to turn speed.