Maybe the difference between the Fate Sisters and reapers is that the Sisters simply create the catylst for death to occur, whereas reapers are the condouit used to bring soulsover to the other side. That being said, wasn't it a reaper in "Faith" from season 1 who was being used to kill people?
That was my interpretation too- Fates decide the mode, manner, and timing of death, whereas reapers come and collect afterward. This episode also confirms what I think alot of us were thinking- that souls equal power of some kind in angelic battle. Can't wait to see where they go with that. I love Cas dearly, but hate to think of what he might have done...such is the case with war. One way or another: Blondie, 1979.