He steps back to avoid the longsword even as the liquid splashes; it should become apparent that even fancy elves have bad language because he certainly hisses something even as he sheds his now ruined top layer, letting it fall to the ground. He can do nothing about the pain he currently feels, unable and unwilling both to discard the pants even as the acidic liquid eats through the leathers and cloth in a few patches. Adding to that problem is the need to step around the puddles-- and turn his attention on the warrior with the longsword, hoping he was hit harder by the liquid than Thranduil himself.