The rules state that anyone engaged with the stone while lightning strucks is hit for 1 stress, 1 wound and 1 fatigue.

But there is also a more severe rule, for a DIRECT hit. How can a character get a direct hit? If he is engaged he gets hit for 1 stress/wound/fatigue. Is it different than in the first case where they are simply engaged with the stone? And how can the GM 'target' a PC for a direct hit?

I ruled that the lightning strikes a PC directly if one of them is carrying a stones while not moving (when the lightning strikes).