There are a bunch of ways to make humans a threat some general others more specific.

General Ways
  • Headshots - Hitting the head (+2 difficulty, +1 damage) with a firearm changes it from bashing to lethal damage to vampires, making a competent shot capable of being a threat.
  • Fire - While it takes a little more explaining as to why they use it, once a human knows about fire's effects on vampires they get much scarier. Not only do you have aggravated damage but you have the chance of rotschreck which sends the vampire running and could give the chance for the human to get away.
  • Daytime