I believe that during that time period there wasn't a choice about adding the crafter's mark so those items were made by a crafter prior to becoming a grandmaster.
You are correct. The maker mark toggle I don't believe had been put in yet. The ones that are "made by _____ [exceptional]" were made by a GM crafter and the ones that are simply [exceptional] ones were non-gm.
What I meant is thatI am particular about the crafter names in my collection as I prefer them to be rp based such as a material type or someone famous. A couple examples from my collection are "a cloak made by marble [Exceptional]" (I'll eventually get it colored like marble too) and "A skinning knife made by The Guardian [exceptional]". If it doesn't fit that criteria, than I prefer the ones simply marked [exceptional] without the crafter mark. I'm the same way with sewn clothing.