No, the low raw damage requirements means that most of the time, people typically get the max % chance knockdown for their weapons. I don't use the light spiked club, but it has terrible base damage and pierce. Without speed bonus/holding, you'll need a decent 7-8 PS hit to easily reach 40 raw damage with 20 pierce. Also, it's highly likely that the knockdown tag doesn't work with the pierce damage type.