Unless otherwise specified, abilities default to and target cards that are in play. For example, if you have a weapon sitting on one of your opponent's characters, and the Hebrews 10:39 LS (otherwise known as the Destruction LS) is placed in your LoB, so long as lost souls aren't being negated by a card (such as the Cloud Moses, or the FBTN LS) then you can discard that weapon. Same scenario if it is a territorially placed enhancement such as Paying Taxes, Treasures of War, Gamaliel's Speech, Kinsmen's Agreement, etc. It can also target enhs in your opponent's Storehouse.
Example: Let's say your opponent has two Armor of God enhs on one of his characters, and during your draw phase you draw the Destruction soul. Once you place it in your LoB, you can discard one of those armor enhs. Then, if you put the Destruction soul into a site, you can discard the other armor enh.
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