Any item made with Demonite Bars will emit a small amount of shadow particles.
110 Demonite Bars (or 330 Demonite Ore [as of 188.8.131.52]) are required to craft all of the Demonite tier items along with an additional 56 Shadow Scales.
Any Items created with Demonite Bars are worth as much or less than a single bar. To gain money faster it is wise to defeat the Eater of Worlds or the Eye of Cthulhu, refine the ores into bars and sell them whole.
When Demonite Bars are created the sell value is worth 8 silver more than the value of 3 Demonite Ore.
Demonite can be easily found around the Corruption in groups of 2-5.
Items made out of Demonite are faster than their Crimtane counterparts, but deal less damage per hit.