As we have already established, Pinwheel is a necromancer who stole power from Nito to bring back his dead wife and child. It has been speculated that he managed to combine the three of them as one being, and that would explain why he has six moving limbs and the three different masks. The boss fight music has the sounds of a man whispering “I’m sorry,” indicating that the former valiant father is apologizing to his resurrected family for fusing them together as a monstrosity.
This brings about my theory of the three family masks. In human history, death masks were once used as mementos of the dead, or to be used for certain portraits. With the theme of death and resurrection being common in the Souls series, it would make sense to incorporate these masks as items to equip. As far as appearances go both the Mask of the Mother and Child are eyeless, however the Mask of the Father is the only one to have eyes present. In addition, they appear to be wide-open, possibly in surprise of something.
So here’s what I’m thinking: the Masks of the Mother and Child are eyeless because Pinwheels wife and child have been dead for a while, up to the point where their eyes have completely decomposed. Pinwheel held on to their rotting bodies until he stole enough power from Gravelord Nito to re-animate them. However, whatever method (say a spell or miracle) he used backfired and they ended up combining as one creepy being. I suspect that the reason the Mask of the Father has that surprised expression is because that was Pinwheels final reaction right before his spell goofed and these three death masks were formed.
The fact that his wife and child’s bodies had already decomposed supports my reasoning of why their masks don’t have eyes, just vacant holes with their skull underneath (notice how they don’t show the players face when equipped, just blackness i.e. the remaining skull). Pinwheel is remorseful that this happened (imsosorryimsosorry) and was researching how to fix it before being slaughtered by the Chosen Undead. Perhaps Nito took pity on him for his failure and forced him to guard his tomb as a Gravelord Servant while continuing his necromancy research. This would explain why he has weaker versions of himself guarding Nito’s tomb. This is just me thinking out loud here but I would be interested to see what you guys think.
Also, I have another theory about the Mask of the Father. Some earlier Pinwheel speculation thread had concept art of Pinwheel being composed of three people, two individuals on top of one other person. With all pictures of Pinwheel, the Mask of the Father is always the lowest mask of the three. This is because whatever remains of the original valiant father has physically been carrying his fused dead family on his back, which would require high endurance. In my opinion, this is why the Mask of the Father increases equipment load. Pretty morbid stuff if you ask me.
TL;DR Mask of the Father reflects Pinwheel’s screw up and having to backpack his dead family.
EDIT: I finally found the pictures I was describing from a previous thread, they are taken from an artbook that shows Pinwheels early development.
I figure the way they are stacked is the Father carries the mother, who carries the child and they are all fused together. Also, the Japanese name for Pinwheel roughly translates to “Family Weave,” further solidifying my theories.