For as rough a sketch as it is, it looks good.
Suggestion: If the Spectre runs-out of P.P.E., (s)he is pulled back into limbo for a random number of days/weeks while (s)he recharges.
Optionally: If there is a death within a certain radius, the Spectre can syphon some of the released P.P.E. (up to 25%, say), without harm to the released soul. Draining more (of each 10% additional to a max of 95%, since we can't alow the destruction of a "soul"...
) can cause problems with the soul, diverting it, causing it to loose it's way, etc. (poltergeists, tectonic entities, etc could be created this way), and do bad mojo to the good/bad "bar" you mentioned.
Personal Note: This does seem like an excellent idea, and a very gameable one too. However, this looks like atleast a two-rifter kinda thing where you to submit it and it was accepted. Almost a source-book of it's own!