[KCD2] Question on crafting tier 4 weapons!

I have the perk for tier 4 crafting, tried to craft a knight axe tier 4. I don't think I overheated or really even hammered in the same spot. I've just heard contradictory answers previously.

Do errors in crafting affect tier outcome or is it solely related to craftsmanship level? (Which I know I can buff with potions, apron, gloves)

Is it just a few quest related weapons that can't be tier 4?

Any insight would be appreciated!