This question of wristbands increasing SW is interesting, especially in hot weather as they can absorb a lot of weight in sweat.
In another thread I noted that while SW calculators such as TW's show virtually no increase in SW when adding mass towards the butt cap I've felt a loss in maneuverability and RHS speed when adding mass there. I've also noticed an increase in RHS when reducing weight near the butt cap and under the grip.
Since a consistent stroke means NOT usng the wrist alone and instead using the shoulders and core to swing it stands to reason that an increase in mass anywhere on the frame and even the wrist will reduce RHS. The effect will still be greater towards 12 but still of significance near the butt and even the wrist.
In other words, these SW calculations (eg TW's) using a point on the handle as a reference point are wrong imo. They don't match real-world experience and they don't make sense based on a proper swing as opposed to a wristy-swing.
Only on Talk Tennis can you find people who believe
that 10 feet of lead tape has no effect on a frame...