Flip that. Any weight you add to the butt end of a club will reduce the swing weight. The basic math is adding 2g of head weight = 1 SWP increase change, or adding 4g of grip end weight = 1SWP decrease. So adding weight to the head increases swing weight, while adding it to the butt end decreases it (by a smaller factor). The head weight rule moves around a bit based on club length also. Adding say 4g to a driver will change the SW more than adding 4g to a PW.
All that being said, SW is a very subjective thing. Some people will pick up on it far more than others. Some people will notice a total club weight change more than a swing weight change. Golfer dependent. But again regardless of what some people on here try to say, the putter is a different animal and the impact of swing weight will be less obvious in it. That is why if you look at pro golfers who put lead tape on their putters, it's almost always large amounts of it, not just a piece or two. It just takes more weight to make a difference with a putter.
