Technology in the Cosmic Era can become corrupted and infested. When this happens to a mecha, the result in codenamed a Hekatonkheire.
The Suit of Purity appears to be one designed for the heroic, but it masks it’s true villanous nature. Anyone who wears it for long is bound to be slowly twisted to the Dark Side.
In seeking to escape serving the Lord of Ravens many a hope flickered and died, for those who oppose him end up serving him after all.
A fine suit of armour that provides protection, but from what?
The local band of 'nasties' (goblins / orcs / whatever) lives in relative peace with the local population.
Along come the PCs and go through their usual heroic monster bashing routine, wiping out the nasties and pinching all their stuff, then continue on their way.
Problem is, they don't kill ALL he nasties. The survivors want revenge and, after spending a few months recovering, start to take it in their own inimitable style (which is not unlike that of the PCs come to think of it).
Next time the PCs are in the area they find themselves VERY unpopular with the townsfolk.