- For the Neutral and True Pacifist Route counterpart and the item found at the beginning of the game, see Toy Knife and Worn Dagger.
The Real Knife is a weapon item found in Asgore's Home. Plot-wise, it is the Worn Dagger as seen through the lens of a Genocide Route. Its defensive counterpart is The Locket. It is the Genocide Route weapon item associated with the First Human, and is implied to belong to them.
- If the Real Knife is hacked into the inventory on a non-Genocide Route and is equipped, most monsters can be spared on the first turn (even most non-spareable monsters), noting that the monsters fear the hostile nature of the weapon.
- The existence of this item may be a reference to a rumor from the Undertale Demo, which stated that in contrast to the Toy Knife (which is obtainable normally in the demo and the final game in the same place), a Real Knife was supposedly able to be found somewhere depending on the protagonist's actions. The item's Steam Badge description, "A symbol of the bond between player and character.", makes a callback to this rumor.
- Within the context of the final game, this bond may refer to the bond between the player and the first human, as together the entire world can be erased, something which cannot be performed by either entity alone.
- Despite being the strongest weapon in the game, it (intentionally) never sees any real use without hacking as the last enemy has only 1 HP. The same applies to The Locket, the strongest armor in the game (as the last enemy can only deal 1 damage per hit).
- It is heavily implied that the Real Knife and the Worn Dagger are the same item, but since the protagonist has a higher LOVE in Genocide, it is described as a killing tool rather than a gardening tool.
|Consumables|| Monster Candy • Bandage • Spider Donut • Spider Cider • Butterscotch Pie / Snail Pie|
Snowman Piece • Bisicle / Unisicle • Cinnamon Bunny • Temmie Flakes • Abandoned Quiche
Dog Salad • Astronaut Food • Instant Noodles • Crab Apple • Hot Dog...? / Hot Cat
Glamburger • Sea Tea • Starfait • Legendary Hero • Bad Memory • Last Dream • Popato Chisps
Nice Cream • Junk Food • Steak in the Shape of Mettaton's Face • Hush Puppy
|Weapons|| Stick • Toy Knife • Tough Glove • Ballet Shoes • Torn Notebook|
Burnt Pan • Empty Gun • Worn Dagger / Real Knife
|Armor|| Bandage • Faded Ribbon • Manly Bandanna • Old Tutu • Cloudy Glasses|
Stained Apron • Cowboy Hat • Heart Locket / The Locket • Temmie Armor
|Miscellaneous||Punch Card • Annoying Dog • Dog Residue • Undyne's Letter (EX) • Mystery Key|
|Cut Content||Croquet Roll • Rock Candy • Pumpkin Rings • Stoic Onion • Ghost Fruit • Puppydough Icecream|