how I lost over a pound of rear unsprung weight

[Fuzzy]

Sprung weight is supported by the springs in or around your shocks. This is most of the weight on your NC. Un-sprung weight is between the road and the springs such as wheels, and swing arms. Brakes are mounted with the wheels and thus "un-sprung"

 

[Akar.Zaephyr]

Uhhh ''un'' ?

I was riding a 50cc Kymco scooter before NC and as you know, the entire engine and CVT is at the same time a swing arm, adding up to the unsprung weight a lot.
Every time I hit a hole in the road, I could hear my teeth jingle and my spine crying.

So, to answer your question: shock absorber is the component that absorbs shock and vibration from the swing arm, wheel etc. But the swing arm/wheel itself has fairly limited shock absorbing capability, only tire softness being tiny bit of absorbing ability. The heavier the swing arm, wheel etc. or basically - part of suspension that doesn't absorb shock but transfers it to shock absorber, the tougher vibrations are to be countered by the shock absorber.

So the "unsprung wieght" relates to those suspension components that do not absorb the shock, but transfer it to shock absorbing component. And the heavier they are, the harder it is to smooth out the ride.