The title is " Threads,too, are easily severed." It may indicate that the dark haired guy can help to get the third arm off easily. (In some Asian countries, thread has the meaning of links between a couple.) The third arm ties the two together so the dark haired guy get it off only when it attacks its host. Since he does not want to cut the link thoroughly and use that arm as an excuse to take care of or enjoy the reliance from the third arm guy.
The title is " Threads,too, are easily severed." It may indicate that the dark haired guy can help to get the third arm off easily. (In some Asian countries, thread has the meaning of links between a couple.) The third arm ties the two together so the dark haired guy get it off only when it attacks its host. Since he does not want to cut the link thoroughly and use that arm as an excuse to take care of or enjoy the reliance from the third arm guy.