35–45% of Physical Damage converted to Fire Damage
12–16% of your Shield's Armor, Dodge, and Barrier added as Fire Damage
Blocking with a Shield stores Cinder for 4 seconds. Your next primary Attack consumes it to add Fire Damage based on the Shield's Armor, Dodge, and Barrier. Blocking again refreshes Cinder.
A shield stopped the blow. The hammer remembered it as flame.