I think Faith would have been dangerous either way. She was already shaped by her childhood. She was wild and didn't acknowledge authority. Being the Slayer may have helped. It put her in situations where she got to see and experience darkness first hand.
But she reveled in the kill, where Buffy didn't. Proving that the lust for violence wasn't a slayer trait. That was something all of Faith's.
But she reveled in the kill, where Buffy didn't. Proving that the lust for violence wasn't a slayer trait. That was something all of Faith's.