I always wondered whether he was just a Samoorai Bushi in decadent armor or some sort of Mooshu type clockwork. I tend to question whether he is actually alive because unlike a Samoorai Bushi you can't see any flesh whatsoever, even in the holes in his mask. Maybe he's like a magic suit of armor or a guardian spirit inhabiting a suit of armor. That sounds more like Mooshu legend than anything else I can imagine.
The metal guardian looks like he is wearing a traditional Beijing Opera costume symbolizing 'armor', complete with banners. I do not know if there are different costumes in the opera tradition for guardian figures vs mortal ones, but this seems similar to a general's costume I have seen. (These armored characters can be both male and female, by the way, such as a female general). They are also brilliantly colorful and delightful to see in performance! This is another excellent example of KingsIsle's artists and designers bringing out historical motifs in their imaginative world. Virtuous Anne Radcliffe
The metal guardian is one of the many elemental guardians located on the Giant Turtle. I think the metal guardian is the hardest guardian to defeat. With over 3000 health and his "not so tricky" yet sharp traps to solve the puzzle. Although I won I think some pirates may have lost the battle.