Hit chance helps with it, you cast shield bash, and you have a short time to hit with it, it takes mana when casting and lasts based on parry & weapon skill.
proccing on a weapon hit OR a successful parry hit chance would be more beneficial imo than relying on a parry chance.
I'm not sure about wrestling counting as a weapon skill for this, but you'd beable to tell if the duration is too short it's 5 seconds with 120 swords/parry, if it's less than 5 seconds with wrestling you'll have your answer.