My thoughts concerning the effectiveness of the psi shield would depend upon two major factors: 1) how powerful is the initial psionic pulse versus how strong is the armour rating of the shield. The basic idea I was thinking of was a comparison of body armour versus the caliber / energy level of the round. There are several levels of body armour ratings that would increase their protective rating when you start tossing in tech levels. This could also allow for how comfortable the device would be to wear. This would also allow the temporary shielding of a room or even an entire ship, if there is enough power, however, it would probably be detectable to a newborn psi baby out to the orbit of Jupiter. So you have the means to do it, however, at what cost and at what level of noise level would you be operating. My three cents worth, (got to account for inflation.) however, your mileage will vary.
Keith