This is really annoying, i can only get it to exquisite, i am rank 30 so i dont know what the issue is.

Do you have the Daedric Perk?

^^^^^^^
This.

Elixir of Blacksmithing.

Yes. I can create Daedric

Yeah, you need to have the Daedric perk (or wear a bunch of smithing boosting gear) to get it to legendary. This is the case with all armors. Without the perk for the gear type, your improving is limited. Thus it is very difficult to ever make Hide, Iron or Leather gear Legendary, since none of them have a crafting perk.

If you have the perk and can't hit legendary with 100 smithing skill, it must be a bug. By the time I hit 90-ish skill, I was already making legendary glass armor.

But i have the Daedric perk! I can create daedric!

Daedric Perk,Smith 100-(easy,make daggers)Enchant 100-(easy,enchant the daggers you smithed) Enchanter's Elixir to boost enchantment on Fortify Blacksmith and make 25% bonus to Smithing for Ring,Gauntlets,Necklace,then Blacksmith's Elixir when you forge the weapon/armour/improve it. Ta-da,all powerful Dragonborn Hero/Psycho.

So then it must be a bug. Just go get some potions with +smithing

Have checked to see if you are diseased? I'm not sure if there is a disease that affects smithing, but I suppose there could be.

I also enchanted a tunic for this. I guess you could enchant the Blacksmith's clothes to be authentic.