For those guard players, have you ever absolutely needed to keep a unit at bay? Well there is an almost guaranteed method, provided you have ordanance barrage and at least a unit of 8 psykers.
If it is absolutely necessary, you can reduce a unit to leadership 2. You can then fire ordanance barrage at the unit which reduces their leadership all the way to 1. Mission accomplished. Automatically pinned, even if you only kill 1. It is important to remember that snake eyes on 2d6 only automatically pass morale checks, not pinning checks.
This is incredibly situational, but 3 griffons and a unit of battle psykers almost guarantee controlling a non fearless unit when you absolutely need it.