Technically, he should be overpowered to the point where he would occasionally find a challenge but nothing that tough.

Not that I want it easy, but considering that his gear is enhanced by smithing and enchanting, I would only expect him to actually sweat on Master or Legendary.

He wears a set of Stalhrim armor (Legendary) with Fortify Heavy Armor, Fortify Health and Resist Fire/Shock, not only on the armor pieces but also a necklace and ring.

Still, Fire/Frost breath attacks from Revered/Legendary dragons do a lot of damage, and one of these days he got an asskicking from a nightlord vampire and a vampire nightstalker in Pinemoon Cave.

I still killed them, but it didn't exactly feel like a glorious victory.

How much damage does your weapon do?
whats your armour rating?
What is your enchantments strength?
how much health have you got?

My 2H weapons have a damage input of 100~something. Same goes for my bow.

298 without the ugly helmet. Instead, I use Dragon Aspect if necessary.

My enchanting skill is lvl 100, with all perks available.

Dude... 600+.

Okay well if you want to learn how to make your weapons/armor stronger, or just your character in general, there are plenty of guides for that.

But I will say that Armor skill enchants are a waste of space, you would be far better off with +weapon damage, +magicka resist, or stamina/health. You can reach well beyond the armor cap with just smithing, especially on stalhrim. But you need to level alchemy as well.

Even without alchemy, Expert difficulty should be easy for you. For enchants, I recommend Archery/Fortify Restoration on helm, Fortify Restoration/+Health on chest, +Twohand damage/Archery on gloves, twohand damage/Resist Fire or Stamina on boots. For your rings and amulet, just enchant them with twohand damage/archery. If you dont use your bow very often, and you find youre still dying, you can sub the archery enchants on your rings for magicka resist, Blocking, or health.

Use the Lord stone. The Steed is a convenient stone to use, as are the skill improving stones, but for survival, the Lord stone is best. Also, if you can level alteration high enough to get the +30% magicka resist, that helps a lot too.

Put a few points into the block skill, it helps a lot even when using a twohander to block.