Shear doesn't message it's "weakening" via Power or Perceive, and it doesn't seem to trigger at all if Psy Shield is up. Dispel vs Psy acts the same as dispel vs Psy and Shear, at capped mana, with no shear messaging at all. When Psy is dispelled (after 4-5 casts for our testing), shear goes with it, without ever messaging at all. I would like to see psy weaken incoming casts that then were subject to shear, much as SOD should act with shear consistently in 2.0. Shear is just being wonky (technical term).