The third line makes me think of Tonberries' Karma attack, which deals damage based on how many fiends, or "souls", you have killed: is it anything to do with that? Bribing Tonberries earns you Amulets, which can be used for Mix or to customise Pickpocket onto armour. And the first line could well refer to Bribe, since it 'solves' two problems at once; defeating the monster, and collecting rare items that in some cases, you can't get from Stealing or as drops. So, though I'm probably way off, I'll say Bribing Tonberries.