Probably already suggested, Molotov or light with alchohol.
This would add burns to the zombies or the human, dealing damage. The zombies fire or humans if it is near another object would spread, so if someone lights you on fire you can accidentally spread it to yourself.
And this can be used to heal bleeds, because as you know fire can stop bleeding and clot it, this would be great help, either this was regen some health or
Another feature is with enough bleeding you start to take damage, so if you were 10 percent health without proper care you could die
Now the objects
Alcohol - heals and works with fire
Lighter - fire that patches wounds or burns people
Molotov - fire
Any more suggest below!!