According to Wikipedia, the Pluto symbol on this card is the astrological symbol for Pluto and the more familiar "P" like one is astronomical symbol.
I like the Pluto symbol on this card because I think that Pluto is a good association, however, I have a slight chronological pet peeve with this, in that this deck is based on Renaissance symbols and imagery and the planet Pluto wasn't discovered until 1930. But I'm getting over it!
I read in the book that those winged hearts are supposed to represent the souls answering the angels call. So much like the rising corpses I suppose, but I totally missed that association!
I do prefer to see this card in general in terms of a more "personal" sense of judgement, rather than a cosmic one.
For me, it sometimes refers to the need to
really acknowledge your own mistakes and not just recognise them but accept them and forgive yourself for getting it wrong. If you live in a state of constantly beating yourself up for your mistakes instead of accepting them and forgiving them, then you can never grow or develop any further. In a way, you're creating your own purgatory. This is why this is such a tough card in many ways... it is often easier to forgive others than to forgive yourself.
So to me this is sometimes about accepting mistakes, accepting that perhaps you made a wrong choice, an error in judgement or have veered off course, but this is your call to get back on track, everyone deserves a second chance! And with this card, I think you are being given that chance.