So i have daedric smithing perk, i can make daedric things to ledgendary i dont understand what is up with the mace.

Most uniques don't use the perk so you'll need 100 smithing to get to flawless.

max smithing, and the best smithing enchantments you can possibly make + smithing potion~

Aren't levelled items unable to be upgraded past a certain point? What level are you OP, or more accurately when did you receive the mace? As far as I know levelled items stop being upgradeable at 46 and above

The mace isn't leveled, like most daedric artifacts thank god.

You can't upgrade it because it doesn't take effects from daedric/ebony perks (the 2x benefit) so you need 160 smithing skill to upgrade it to legendary. You can get that 160 by enchantments/potions.

Daedric quest items aren't leveled.

edit: beat me.

YAY! Makes me happy, good news to hear

I am level 29 received the mace at 26