Yea, blatant murder and assault isn't justifiable to most good deities or codes of ethics, even if the target pings as evil. "Oh this shopkeeper is evil? Guess he dies."
At the least, it's highly illegal most places, so even if there aren't divine consequences there'd certainly be social ones.
Supreme judicial power derives from a mandate from the masses, not from some farcical abuse of a magic item. I mean, if I went around stabbing people just because some moistened bint had lobbed a scimitar at me they'd put me away!