Again there is a lot of conflicting evidence, firstly on that first study there is a very good chance of the placebo effect as the patients knew that they were wearing the band.
Here is some more conflicting evidence
Myth Busters episode
Study with recduced placebo effect
Report on Accupressure
It's pretty controversial but most of the evidence points towards it being a complete placebo effect, there are other theories but it seems most likely to be a placebo effect. Even the last study admitted that the placebo effect can be more effective than normal medicine, it is certainly feasible that this is the case.