So booken, the dwarf armorer and so on can all craft one "ultimate" piece each from what I understand(only got bokken´s myself) so were curious if there is any special requirements before you can get the items? Guessing specific quests like Bokkens quest to test out his potion on different things and the dorf smiths quest to find pieces of his family armor? But after that is it just a random chance each time they come with an item that you can get the ultimate item?

They need an arbitrary thing called master level. It is composed of master quest status, their province stats, kingdom stats and their building level. How all of the above exactly affect master - nobody knows. Maybe, devs do, but I'm not sure about that either or it would be in tooltips or something along with other kingdom information that is not disclosed anywhere.

basically every "master level" has a thing they will make that is slightly better than the last one. problem is it is not displayed anywhere and we don't know what exactly we order. You can order a weapon and get boots order a crossbow and get a shield, etc - totally internally consistent design(as in nothing is explained or depicted ever and the game blatantly lies on top of it).

there was a reddit post with master rewards listed. it is better, than nothing. post is called "Artisan Specific Items List" in case you want to search for it.