actually now that i think back to it, hank wasn't a bad witch hunter, he just didn't account for the fact that shit is crazy. we find out that precious is alive and she was shot with a silver bullet, which i guess should be game over for any witch, but she's alive still. So hank went in there guns blazing shooting the black hair salon with silver bullets, thats why he didn't check to see if the witches were really dead when he shot them, thats why he discounted precious, cuz of the silver bullets.
i'm thinking voodoo/witch magic is shared in a collective pool of power and since like there are so few of them left, a lot of that power is being funneled into which ever witch is still around... the young witches at least. That would explain how all the young witches got so powerful... they killed nan cuz her clairvoyance was getting more powerful, let alone her growing TK and mind control. Madison could raise the dead and who knows what else, and zoe has like super witch book smarts now.
but again i think this only affects young witches, that would explain why fiona keeps on deterriorating, why mrytle (the burned witch) doesn't seem so powerful (maybe a tiny power bump... cuz she died) and why cordelia had to go re-blind in order to get second-sight again.
regarding the SEC rat maze... maybe it could only be done with 2 super powerful supremes? was angela bassett helping out? i don't really recall, but that'd be my explaining on how basically Warren Buffet got taken down.