If anyone has ever read a horror story in the past, they are probably aware of one thing; the main protagonists are usually not that capable in fighting back against the killer.  When fighting for their lives, most main characters tend to not pick up the very reliable pistol or axe right in front of them.  Instead, they fight very offensively, using their mere fists in the hopes of at best bruising the entity after them.  If some type of saving grace is not presented to the main character at the last second, this type of fighting usually ends in their untimely death.  That is not counting the other one -third of the time where the main protagonist tries to run for it and fails due to a buffet of clichés halting them.  In both cases, the character could have been saved by simply picking up the weapon next to them and not breaking complete logic in the process.

For those still thinking fighting offensively against the killer is effective, think about what the characters in other types of horror stories do.  When confronting a vampire, the characters make sure to carry at least one wooden stake with them, and if near a church, tons of holy water stored in a sealed container.  In situations with a werewolf, characters almost always wield a pistol with a silver bullet in it; the kryptonite of hairy man wolves.  With giant spiders, the best solution is a blowtorch with tons of gasoline loaded into it.  Heck, The Ghostbusters even found a way to contain spirits by using a special type of vacuum!  All of these characters are somehow allowed to wield weapons while most other horror related characters are too stupid to even try.

The most prepared type of characters in a horror story though are those fighting against undead zombies.  As cliché as it seems for many characters in zombie stories to be wielding guns, especially if you account for the noise and weirdly unlimited ammunition, it actually makes some sense survival wise.  When you are trying your hardest not to be bitten by the undead, a fast moving weapon like a gun may be your lone defense against getting the heck out of a hoard.  Sure, the characters lose some points in realism for being perfect shots from the get-go, but they win points back in the logic department unlike most other horror related characters by actually fighting back with a weapon.  The zombie apocalypse survivors know unlike most that things are going to get tough against the man-eating zombies, and fighting back with their fists or running for it won't be enough.  Hence, they almost always stock up on guns and usually a secondary weapon like a knife for close range kills.

  So if the cliché zombie survival story characters are allowed to wield weapons, why can't most other characters?  Having them wield nothing against the main threat does nothing for increasing the tension of the scene.  Instead, the audience is going to always smack their heads in disbelief that the character didn't do the logical thing and grab some type of a weapon to defend themselves with.  There is a good reason parody horror movies like Scary Movie love to make fun of tropes like this, since they seriously defy all logic. 

  Now imagine if you were cornered in a garage by some type of slasher movie threat?  You are not for the life of you going to ignore the slew of untraditional weapons around you like in the movies.  To stand a chance of getting away, you are going to wield some of these everyday items and fight back.  A normal item such as a cane may not seem too dangerous at first glance, but when defending yourself against a killer, it is surprisingly effective, especially if the cane is made of steel.  You could bring the killer to their knees by badly bashing their upper legs or if gutsy enough, hit the killer hard on the head.  Gardening shears can become a sharp knife, chainsaws can leave deep gashing wounds on the limbs, and a simple nail can be jammed into the killer painfully with a strong enough force.  Anything in that garage could be used as a weapon against the killer so you can get away and call the police on your cell phone for further assistance.

To make your characters in a horror story more realistic to the audience, they will have to think in a similar way as you would.  Whatever your first instinct would normally be, the character must follow through with it in order to better win the audience over.  Even if using said weapon only buys them a short amount of time, at least the character goes down in  a death made much more memorable by the sole fact they weren't stupid enough to ignore any type of defense in front of them.  It could make the most cliché of horror stories have a tiny bit of substance in them that the audience is not going to forget so easily.

  Weapon usage in a horror story is the difference between stupidly incompetent characters and those with even an ounce of logic.  One makes the audience extremely frustrated while the other gives the audience a satisfying type of surprise from the typical horror story.  Whenever you put your character in a situation in which they are put in a corner in the future, ask yourself what you would do to stand a chance against the killer.  You definitely will not be going out defenseless.