Item: garlic; apply to a freshly opened cut or burn to immediately intensify the pain, adding 1 point of Acid damage to the wound made by a Slashing or Fire attack.
Item: Plastic Machine Gun of Poker Summoning; does not fire any ammunition, but instead calls forth an Ethereal Poker to jab the target repeatedly. (It might just be a wand stuck into a toy gun.)
Encounter: Terwilliker, lawful-evil bard. Has been recruiting, brainwashing, and training apprentice-bards under the guise of a music school, but is actually gathering them together to each play a part in some tremendous world-conquering spell.
Item: the Unabridged Dictionary of Hell: While equipped, the player can speak Abyssal and gains advantage on any speech checks made against demonic entities. However, it is rather heavy, and makes the player look like a total nerd, so while it is in the player’s inventory, they must take a -1 to both dexterity and charisma rolls.
(Twist to be decided by DM before use: it was published by demons and is actually completely and purposely incorrect and the demons go along with it because they think it’s funny; roll d20 with each usage, rolling a 1 has the demon being spoken to reveal the ruse)