Frontal Block
Some skills have the “Frontal Block” property—Punishing Strike, Raze, Flatten, and Axe Counter. These skills will block incoming attacks from the front and always trigger a perfect block; but they cannot block for our party members and do not normally trigger Strong Frontline.
There is a way to trigger Strong Frontline using frontal block skills—by using Axe Block and then a frontal block skill blocks a hit within .5 seconds of using Axe Block. This can commonly happen when block canceling skills.