How to calculate the "swing heavy weapon as if swing normal weapon" feat?

[Mariogoods]

Recently, I have seen the classic novels and found that it is frequent for them to describe their physical strength by describing them casually swinging heavy weapon. The "heavy weapon" means weapon which weighs 62 jin (31 kg). I'd like to know how to calculate such feat as I feel that it should be higher than simply lifting 31 kg weapon up.

 

[SeijiSetto]

Perhaps you could do something like finding the swing speed at the tip of a regular weapon (like a shortsword) then find the acceleration needed to do that. Then apply that same acceleration to the heavier object, F = ma. Convert F in Newtons to kgf, and you have lifting strength.