Sting

Sting is a diamond sword available as a prize from the Wizard Crate. It functions as a normal diamond sword except that it adds a White Glow Effect to all players, including invisible ones, in a radius when held. This effect is only visible to the wielder of Sting.

((I haven't been able to experiment with this item, but from the brief time I had it, it seemed like it highlighted players within about 50 blocks and the effect lingered for a bit after switching items. If anyone could confirm or correct this that would be great.))