I guess this is proof that the pendant has some measurable mesmerism effect.
That's true. How I've seen it so far is that the pendant can *control* people very effectively, even to the point of implanting post-hypnotic suggestions. Like with Pearl - it pushed her to go the distance with Adrian. But I don't think it changed what she wanted - her reason for enjoying that encounter had more to do with her being (wonderfully) oversexed in general. The Watch, on the other hand, appears to be able to change people's desires on quite a fundamental level - and instill love, and so on.