Stagger meter increases from all hits when shield is raised, not only blocked

The stagger help tip states:



But all hits taken when the shield is raised increases the stagger meter. This can be easily tested by raising your shield and standing with your back against a monster. Also tested so that it's not passive block that increases the stagger meter. Non blocked hits increases it as well.

Edit: Even unblockable hits increases the stagger meter.

Edit: Stagger amount from damage is also increased by stun buildup. This is also not conveyed in the help tooltip.