I want a weapon that's kinda like the upgraded crossbow / VR11, but different.
It shoots something colorful, something that Sam would like to see (like the monkey bomb). I'm not sure what it would be, though. Instead of having to wait for it to hit the ground, zombies near it start chasing it when it flies through the air. When it hits the ground, the zombies realise it's not what they're looking for. Then they stand still and look around for a second to locate their next victim (the player that's the nearest to them).
It seems like the projectile disappeared, but it didn't. After a few seconds it explodes. The explosion creates crawlers if the the projectile got stuck in the ground. If it got stuck in a wall or a zombie, it might kill a few zombies or rip off some limbs. By the time the explosion happens a few zombies have already started chasing the players again and if they're far enough away from the explosion, there's no impact on them. So you'll create crawlers but only a few if you're lucky.
The upgraded version, ofcourse, attracts more zombies and makes a bigger explosion, but it takes longer for the projectiles to explode. Any downed players that get hit with the projectile or the explosion instantly get revived (Krauss Defibrillator style), but there's a risk of getting downed again pretty quickly because the Zombies chase the projectile when it flies through the air.
I think this could turn out to be a realistic wonder weapon. It takes time to figure out the right time to use it, since it can cause trouble for other players or maybe even the user since it makes some crawlers that can get in the way and the zombies start going after players before the explosion happens.