A plot-important, handheld digital device.
A Digivice is a small digital item that holds a significant importance to the character, and if lost, can have a significant impact on the plot. The digivice is also unique in that we immediately recongnize the character for owning one. It could be their signature item, and without it, the character wouldn't actually be the same. The Digivice can have multiple functions, or a single important function, so long as the important function is needed to help advance the plot. It is also near indestructible, often working perfectly underwater, after being dropped from a great height, or being tampered with (which may also be impossible to do). Sometimes enemies may try to steal the Digivice, but most of the time, the item is ignored. Funny how if this item was stolen, it would put to antagonists at a great advantage, maybe to the point where the heroes could easily be defeated. If the enemies do not know about the digivice, then when seen, they may mistake it for a watch or a cell phone. The Trope Namer is the anime Digimon, where in each series the children is given a new type of Digivice. The original digivices signified the children as being not only the chosen ones, but it also helped their Digimon parters to evolve, as well as allowed them to pass between the human world and Digital World freely. What seperates this from a usual Plot Device is that the Digivice is digital, easily mistaken for something unimportant, and can harm the hero if lost or damaged.