I am now the proud owner of a brand new shiny Doublade, and I love her so! My only issue is that the world sprite for her doesn’t actually represent her red blade. So I have fixed this!
If anyone wants to use these more accurate sprites, just replace the ones in the “Characters” folder (679s and 680s) with these. And if by any chance a dev sees this, please feel free to slot this into the files so that these beautiful shinies are more properly represented!