How exactly do staggers work?

[BrowneHawk]

So as a new player its easy to figure out that if someone else is sheilding up, a kick can stagger. Sometimes blocking with a weapon staggers someone on attack. Sometimes it doesn't.

I heard weapon speed is a deciding factor, heard another say it was armor. So what are the different ways someone can get staggered other than getting kicked while sheilded.

[Onatar]

The stagger after a perfect block only happens when you block a quick (uncharged) attack.
Charged attacks being blocked results in no stagger.