Fear rises from a mind thrown forward into what has not yet come. The moment attention returns to what is here, that pull loosens, and a person feels held by something wider than their own thoughts. The words fear thou not are not a command to grip harder. They point to a presence already underneath the trembling, closer than the next worried breath.
To be upheld by that right hand is to rest on the aware stillness that does not leave when the ground shakes. Dismay comes when a person mistakes the noise in the head for the whole of who they are. Underneath it, the deeper self stays quiet. Strength is promised there, and it arrives as the fear thins.