Some minor comprehension questions about this card:

Steal the Soul
Type: Event
Faction: Silver Twilight
Cost: 1
Action: Choose a character you control and a character an opponent controls. Choose one of those characters to gain the icons of the other character until the end of the phase.

So my character gets the icons of an opponent character.
Does the opponent character keeps his icons? ("Steal..." somewhat indicates, that someone gets something and another one loses something.)
Do the opponent's icons stack with my character's icons or do they get replaced?

Well, it doesn't say anything about the other character losing icons, so I would say it keeps them. Otherwise it would have said something like one character gains the icons of the other, and the other character loses those icons or something more elegant but in the same vein.

+1 to TheProfessor. The card also costs 1 and doesn't require any sort of sacrifice, so that would be extremely OP for it to cause a pure swap. The reason I say it'd be OP is because it costs just as much as Binding and does twice the damage.