I wanted to tie it to a move requiring Perfect Balance, but there really just isn't one in which adding a knockback would nullify the point of the ability, and abilities requiring shields faces the same problem. SM only has two abilities that require a shield: Crushing Advance and (I think) Redirected Force. Both already have extensive effects. We can't tie it to Crashing Wave because the knockdown is needed to position the enemy for the knockback, a tactic which is extensively employed by every other tank in the game.
Instead of trying in vain to find an ability that defensive shield-users would use to tie it to, let's tie it to an ability that offensive greatsword wielding builds DON'T use: Graceful Strike.
Currently, no one uses Graceful Strike outside of PvE tanking. Khaine builds with greatswords avoid the ability like the plague because Ensorcelled Blow is superior damage-wise, and has a strong DoT with Ensorcelled Agony, which every single Khaine build uses. However, that does not change the fact that greatswords can use it (even if they don't want to), and I am also in favor of incentivizing more SnB for SM. Therefor, I propose the following:
- Change Graceful Strike to require a Shield.
- Change the Forceful Shock talent to apply its knockback to Graceful Strike instead of Blurred Shock.