Fear has various meanings depending on what's causing it. Sometimes fear signifies love. Fear, as in Genesis 28:17, signifies a holy change.

(Referenser: Apocalypse Revealed 511)

511. And great fear fell on those who saw them. This symbolizes a disturbance of the mind and alarm at Divine truths.

The symbolic meaning of fear varies, depending on what it affects. Here it symbolizes a disturbance of the mind and alarm at Divine truths, as Divine truths have this effect on evil people. For evil people are terrified as soon as they hear about hell and eternal damnation. But the terror soon dissipates, along with their belief in the existence of any life after death.