You actually have to play Swain tactically. Hes not a faceroll nuker like Annie or Ryze. He reminds me much of Fiddlesticks. Plan your attack, and then focus on specific champion, and try to root as many as possible. I've even seen alot of Swains, standing in the outskirts of lanes, using their root, just like a fiddle waits for the perfect time for ult
But the name in itself, doesnt come from his abilities or the way to play him. It comes from his history, where it was told that he was a fearsome officer, and that the men below him, grew to follow him through fire and water