Buzzkill

 is a gun that fires piercing, bouncing sawblades.

Trivia

 * Buzzkill is slang for someone who ruins fun (in this case, the gun's designer from the Ammonomicon entry), and the gun's name is also a portmanteau of buzzsaw and kill.
 * The pickup text "Sawed On!" is a play on words of the Sawed-Off.
 * May be a reference to the Disc Gun in the game Nuclear Throne which also fires ricocheting saw blades.
 * This item may be a reference to the buzz blades from Ratchet And Clank: Tools Of Destruction.