Dated to be from the same time period as warped alloy weapons blood locks are another form of object magic for which the construction method if it exists has long since been lost. All blood locks are perfect squares which sit imbedded into a flat surface. There are a number of blood locks which have been removed from their original position and placed elsewhere but these tend to be of much lower quality than the originals. The blood locks themselves contain a series of intricate carvings and may not appear to be in the right place to function as a lock but make no mistake even if not immediately apparent all blood locks open something. Identifying a real blood lock from a false one being surprisingly difficult. Then there is the issue as to how blood locks work. When open someone can place some of their blood into the engravings of the blood lock and the blood lock will shift. Disassembling and reassembling itself into a new engraving pattern. When closed a blood lock will not open unless the blood of the last individual who imprinted themselves on it or someone related to them (by blood) places their blood in the engraving. If damaged a blood lock will seal itself shut. The lock itself fusing together making whatever it opens too unobtainable. The housing blood locks are contained within however are not so resilient to tampering. The bastardisation of blood locks by ripping them out and putting them into “more useful” containment units a sadly common occurrence.
Normal use: Blood locks can be found almost anywhere where normal locks would be used. Boxes. Doors. Books. There are some blood locks which are used on relics however in these cases the blood lock is rarely considered to be a part of the relic itself and instead a protective ownership mechanism. Locks may not be immediately apparent. Small blood locks for safes can be found hidden in paintings. Sometimes blood locks are disguised as decorative engravings on a wall especially when other similar non-blood lock engravings are in place.
Relic examples: There are an exceptionally small number of blood lock relics. Consensus is that there was never more than 10 of which only 3 are still in one piece. The sealed armour sets are armour’s where the entire armour is affixed to the body with blood locks. It’s watertight, almost functionally airtight and the locks are on the outside of the armour. Sure someone in the armour isn’t invincible. But they can’t bleed and you’re going to have a difficult time bending the armour out of shape. The only recorded time a sealed armour set wearer lost is because they were knocked unconscious, dragged somewhere else and used a relative to open the armour (at which point it was revealed the unconsciousness was a ruse to be reconnected with their family). There are three theoretical ways to used a sealed armour set. The first is to simply wear it and seal it yourself. But this has the obvious negatives in that if it’s family your fighting they can open it up too. A second admittedly rarer used way is to make a slave or someone else of little importance seal it on you. If only you know who can remove the armour then no one can forcibly remove it from you. The third is to be the last of your family and then seal it yourself. No one has reportedly done this but it is thought that this has happened in the past, hence why the other approximately seven sets are have been torn down into pieces.