And if it fell into the wrong hands, it could be big trouble.
~ Harold's common warning (to Tyrone Biggums) about such dangerous objects/methods/weapons (such as the drug anthrax) are in Chappelle's Show.

Tools that can do good for many people but can be very dangerous when in the wrong hands, especially into the hands of evildoers. They can be ranges from mystical artifacts/weapons to technological ones, or even bestowed superpowers/magical powers which proved to be very dangerous had it bestowed to someone whom later used it for evil (examples of this case would be the Sorceress Power, the supernatural energy which so destructive if used by villains such as Sorceress Ultimecia, made Rinoa Heartilly to worry that the said power would corrupt her mind due to her was bestowed with the same gift, only to revealed that she can also used it for good).

The tools included here must have been in the posession of a villain or villains at least once.