*In earlier seasons, the knife is generally called Ruby's Knife by the characters. Its referred to as just the Demon-Killing Knife by [[Mary Winchester]] in [[14.01 Stranger in a Strange Land]]. Additionally, Dean calls it a Demon Blade in [[12.06 Celebrating the Life of Asa Fox]] and explains to a room full of hunters that it kills demons, "kills them dead."
*Though the knife played a role as the Winchesters main demon-killing weapon in the earlier seasons, it has lost its prevalence in the later seasons, particularly after the revelation that [[angel blade]]s can also kill demons. In the later seasons, the Winchesters use angel blades to kill demons more often the knife which then typically only appears once or twice a season.
*Hunters unconnected to the Winchesters don't appear to be aware of the knife's existence. In [[12.06 Celebrating the Life of Asa Fox]], [[Bucky Sims]] compares the temporary effects of an [[exorcism]] to the effects of an [[angel blade]]. In the same episode, when Dean shows the knife to the other hunters gathered, they are confused, causing Dean to have to explain what it is and its purpose.
*Throughout season 13, the Winchesters did not use the knife to kill demons at all, instead relying entirely on angel blades despite the fact that demons were a major enemy in that particular season. Though the knife appeared in [[13.08 The Scorpion and the Frog]], the only demon killed with it was [[Grab]] by [[Luther Shrike]] while Luther was unharmed when Sam stabbed him with it. The knife was once again used by Sam in [[14.01 Stranger in a Strange Land]].
*The knife was not used by the Winchesters to kill any demons in season 11, but Dean did attempt to use it against [[Amara]] twice and drew it on [[Crowley]] before deciding against killing him. It was used by [[Gunner Lawless]] to kill the [[Crossroads Demon]] [[Duke]] in [[11.15 Beyond the Mat]] however. This was also a season where demons were not a major enemy to the Winchesters due to the greater threat of the Darkness.