Someone from earth reincarnated as an ancient god slaying armor that is currently broken and inside the armor is a body of a dead god and althought the human who have become the armor and obtained its power and the wearer of the armor, is still weak since it is broken and even though its broken it still has its powers that is only weaker than half of its prime, but since its an ancient god slaying armor that is clearly broken it is invincible to things that is not a god. But infront of a god it can still defeat some of it and not all gods it can defeat because its still broken, and when the armour can encounter something that is a god closer to a supreme god then it will likely lose but when its powers is returned to half then it can defeat these but even if all that power its still not enought in front of old gods or ancient gods who have been there before the multiverse existed where the concept of existence did still not exist and the armor have the power to make its wearer capable of going toe to toe with only one of such a being in its prime. And althought the former wearer is a god it is only a god who is still below the supreme god but a supreme god was nothing more but a title to the strongest gods that have been born inside the multiverse not the one that have roamed before the birth of multiverse and one of the old gods is its creator, and because the human transmigated to that armor, the human who reincarnated have no choice but to find a new wearer to slowly fix itself since the armor will not be fixed by itself because it cannot be fixed in the first place without its wearer since it will slowly fix itself and obtain its powers back including the previous wearer's power when it obtained a new owner to put it on. The reason the armor cannot be fixed because the materials of the armor is unknown and the materials are likely born right at the birth of the multiverse or probably because the armor was born along with the multiverse and althought the armor is unknown it doesn't have a consiousness and the human reincarnated to the armor will likely create something worse than the previous wearer of the armor. And also to let you know a dead wearer of the armor cannot trigger the automatic function of fixing itself so the reincarnator have to find a wearer.
This idea came to be after seeing this picture of sam/firefly.