Actually now that they changed mijin us nin can use it in many ways such as to lose hate if we need to for any such reason also if we are about to die and we know it we can simply avoid weaken. so yes nice piece :p
The Attack+10 makes this a good piece for NIN (seeing as it's a DoT kind of job when it comes to DDing) and the Mijin Gakure bonus adds the cherry on the cake. Not sure what the bonus on that is, but I'm sure that it can't be detrimental.