Board Thread:General Discussion/@comment-121.54.32.103-20130408082624/@comment-6192846-20130408111817

My theory is that it is because the Venom Sword and Kayo's Scissors don't have their demons inhabiting them.

In Wiegenlied, Elluka notes how the Demon of Lust just vanishes from its vessel and there is never an explanation given for it. While I have not read Praeludium or Praefatio, I am certain when Elluka gives it back to Keel Freesis that the sword was still empty (otherwise she wouldn't have given it back).

Since the Demon of Gluttony seems to be aware of its own inevitable awakening as the Master of the Graveyard, I am going to assume all the Demons of Sin are trying to reach their point of awakening for whatever reason. Also, since the vessel of Lust's magic is "weak" without its Demon inhabiting it, I am going to assume all their power comes from the Demon.

As for Kayo's Scissors, I am still uncertain but it is possible that there are two pairs of scissors, one which Kayo used that had the Demon of Sin in it, and the pair Gallerian collected.

I could be wrong though.