they learned all the knowledge that she had to teach, and so it was not lost.

I chose to read that line as foreshadowing!

I always enjoyed imagining that Feanor got his compulsive creative abilities and drive from his mother. But I never expected to extrapolate it to the extent of involving him or his sons in needlework or weaving. It has been seen as a feminine task through much of our history. However, with at least one dramatic exception. I had a couple of male friends when I was young who worked as merchant marines, very macho guys, a girl in every port, but they followed the age-old pursuit of sailors--knitting and also doing all manner of needlework. This practice survived well into my adulthood, but I wonder if the computer will replace that creative outlet.

I like the idea of Miriel's handmaidens and how freely they spent themselves and shared their knowledge and created a continuity.

I think you're hinting that the banner Arwen made also goes back to Miriel? I suppose it does in any case, in some fashion or other, but it feels more immediate here.