Malevolent armour degrades after 100,000 charges of combat before falling apart and vanishing completely ('degrades to dust'). It cannot be repaired normally, but two partially used parts (of the same type) can be combined to consolidate the charges - e.g. using a 90% charged helm on a 2% charged helm will result in a 92% charged helm. The armour is tradeable until it is first worn - a warning message is given when attempting to first wear a tradeable part - and partially worn parts are not tradeable.
Retrieving unprotected parts from a gravestone will cause the part to lose 10% of its charges. Dying in dangerous PvP will drop a fraction of the malevolent energy used to create the part, based on how degraded it was, rounded down - e.g. a helm with 52% charges remaining will drop 7 malevolent energy.