We will never really know if Kwan's weapon was 100lbs. or not. We can't prove that he did, but we can't really prove that he didn't either. We will never really know if others had a similar ability.
Anyone that has ever really used a kwan do knows that it is a center weight point held weapon. It is not held by its end. It is not a sword in the traditional sense. Speed in use is determined by how well balanced the lance is.

We can guess, we can theorize, but it doesn't amount to a hill of beans. The past is the past. I for one will not be so arrogant as to pass judgement on something like this as if I am somehow kwans equal. None of us are, not even remotely. I'm not going to judge his strength by my weakness'.

My kwan do is only 25 lbs. In my hands it is not clumsy or slow. I doubt it was in his.