So, here's a weird coincidence:
Tailless consumes souls and in return the wielder gets the power of a Void Hunter. Mibibi makes a pact with it to not eat innocent people's souls, in return Tailless can feast on as many Ethereals it wants.

Similarly, there's the Qingming sword.
It doesn't kill or corrupts, it only eats the memories of its wielder, in return the wielder gets the power equivalent to a Void Hunter's.
Now, what if this sword ends up in one of the siblings hands. What memory will they trade to get the power of a Void Hunter?

>>535576160
looks delicious.