I find that if one has just a shield selected and you use unarmed, that it causes more damage then with out shield. Once you have leveled unarmed up to around 80 and using a shield you can cause allot of damage to Moder when it try's to pin you down. By blocking with shield and waylaying on Moder, you will see the amount of damage you can do.

Basically like Captain America using the shield.