Keep in mind that there is a sweet spot for most players and when you match a shaft with a butt, there are other things to consider, such as does the shaft have a receiver which adds weight to the base of the cue shaft. With my cues, I told my cue makers to build shaft 4 ozs or heavier since the butt’s were 14.5 ozs. The cues have flat faced joints so the shaft weight is just wood, ferrule and tip sans any receiver. Personally. I think 18% is on the low side but i have played with cues with a KW shaft that was on the lighter side for my taste but the darn cue nonetheless played fine. When the shaft is too light, I tend to push the cue ball more with my stroke because my stroke balance seems like it was a short stroke and not as deliberate.