Sam didn't wait for the shadow to make the first move, he slashed diagonally and the sword hit the shadow that just appeared squarely in the chest and a portion of the darkness that is surrounding him vanished creating a large grey patch.
But it is only one-hundredth of the whole darkness. So, Sam has a bitter battle ahead of him.
The two figures exchanged several sword moves, Sam's first move was due to the unpreparedness of the shadow and since then, it became hard for him to land a solid strike on the shadow.
As they were exchanging moves, Sam's skin was being blackened bit by bit. But with his whole body, it was very minute all that was blackened is half of the pinky toe.
But the darkness around him was also receiving damage and was being eroded bit by bit creating grey patches randomly all over the place.
The spirit didn't say anything at all. The eyes on the horizon are carefully inspecting Sam.