Lord Vile's armor is a full set of medieval armour. Completley black, it has a helm which covers Vile's face. It is shown to have the ability to expand and make spikes appear on it at will. Unusually for any Necromancer tool it seems to be made of pure shadow and have no solid form. When Skulduggery Pleasant puts it on it is mentioned that shadows 'wrap around him like bandages'. The suitcase in which he stores it also leaks 'droplets of shadow' which wrap around Skulduggery and form his armor. Due to it having a large amount of magic in it, and magic itself being alive, the armour is able to move and fight on its own, though it has no sentience. It was mentioned as 'talking' to Skulduggery, though this may just be a result of the link between them.
In Kingdom Of The Wicked, Argeddion hides the armour to prevent Skulduggery from becoming Lord Vile. After the trap fails at Greta's farm, the armour is discovered and returned to Skulduggery who uses it to fight Argeddion alongside Darquesse.
Lord Vile, being a candidate for the title of Death Bringer, obviously had a lot of power. It was all channeled through his armour. It can do extraordinary things that no other Necromancer can do. It is noted that whomever wears the armour becomes inexplicably, incredibly skilled with Necromancy, even those who have absolutely no previous experience in Necromancy control - such was the case with Baron Vengeous.