Defensive Theatrics.

[weaw]

I've never seen a removing of off-handed weapon (including shield) through disarming...
For both skills. Entangle and Signature Moves.

But i think the real problem for Theatrics is not a Wars shield. But the tons of endurance and damage absorption/deflection (A shield has some relation to these, but not dominant).
I don't believe that a Theatrics has some chances to defeat a good tank using just a damage. Even if he got 2-4 skills of the Rage part of skill tree. And even if he wields good damaging weapon like falchion or trident. And even if a tank wields an off-handed weapon instead of shield.
I see no more ways here, only bleeding, only knockout (it works very bad on tanks and generally unpredictable), and only some accurate work on stamina (which was described by Kreegan).
For stamina method may help a net. I've already tried to use net and going to try it again (Until i accidentally not fell in the Blood Gods brackets and was not eaten there :).