Is it perhaps a result of the pied affecting the colour of the barring? The only way to see I guess is to try and breed more birds with that colouring. Hens may not look any different, so it may be tough to distinguish them.
The pied hen that is in the breeding pen with him is a sister and the india blue a daughter, so if it is a new colour these hens should also carry the gene, as a chick he was lighter gray than all the other pieds i've bred through the years, there also a full grey chick from his parents but it didn't survive, maybe it was an india blue male with grey barred wings? You never know,
Is it possible the male is split to Purple? I don't know (just throwing out an idea), but perhaps that can affect the depth of dark coloring in the wing bars, since Purples fade over time. Another possibility -- could he have one White-Eye gene? Are any of his oceli white? Others here have said that the White-Eye gene can cause a "silvering" of the wing coloration. I don't see any white oceli in the pics you provided, but from previous discussions here, birds with just one copy of the gene have half or fewer of their oceli white, and some don't acquire white oceli for a couple of years. Did you obtain any offspring from him?
There were no purples or white eyes in Belgium when i hatched him from a normal India blue pied pair, the india blue is a daughter of him and a white eye female, this year he turned four so i should have more chicks of him, the parents i had to sell, because i didn't have any room for them when he turned two, but afterwards said i should have kept his mom also and put her back to him,