Wow, that's some serious power there. Maybe it's the power of the fallen and maybe not. If so then figuring it out is beneficial. If not then figuring it out could possibly make Shiro stronger.
Given that Shiro has power over souls and that she is always so busy I'm surprised she hasn't said the phrase: "So many souls to play with so little time." and then turning to one of her friends asking if they agree.
If Shiro researches about that power and obtains it somehow(without stealing it from Syradil of course). There would be a high possibility that it'll be a key to the cure and a major power up. Though I doubt it since Shiro already has Error.