Tried on Shadowmere Legendary Mode, with and without enchanted gear, same damage with dagger and gloves. So yeah. The Fortify One-Handed enchants does not work on daggers as of April 20th 2017, so you can say, it'll never affect daggers. But the first One-Handed perk do (+100%).
I use a dagger in Left Hand anyway, because 30X dmg is OP. Dual weilding with a sword, mace or axe in Right Hand, you can pretty much one shot everything in Legendary Difficulty by Sneak Dual-Power-Attack lol. ('cause the 30X dmg is applied to both weapons when Dual-Attacking.) The Axe Bleeding effect, the Mace Armor penetration and the Sword crits are useless. The Bleeding is set in stone and don't go up with the Grindstone amelioration. The Armor Penetration is only useful against humanoids wearing actual armor, and we already one shot them easily. The Crit is based on the base damage of the Sword. The Dragonbone Sword does 15 base damage. So when it crit, it does a bonus 15 damage. Nothing more, nothing less. Even if you Grindstone it.
Useful Shouts, Dragon Aspect for 25% more damage with Power Attacks, Dragonrend to force-land those pesky beasts, Summon Durnehviir for the lolz, Throw Voice to distract if needed.
Switching a weapon with Invisibility or Calm when needed and it's melee Easy mode. Pretty brutal too.
And I'm a Vampire, obviously. So I'm 25% harder to detect when sneaking, my Illusion Spells (Muffle/Invisibility and Calm/Pacify/Harmony) are 25% more powerful, I get the Necromage bonus from the Restoration Tree boosting all my enchants and buffs by roughly 10% each... Fem Dunmer too, so no Fire Weaknesses and not too ugly (But I have to say, if you're an Orc and Berserk with all that, you're a monster.)
There's probably a Shout useful with this build, but I'm not quite done with this second playthrough and don't remember all the shouts.
I weared Daedric Armor for a long time, but at this point, there's no need. So I got myself a cosmetic armor instead.
Bone Hawk Amulet - One-Handed Attacks and Conjuration (But you can choose any school of magic or other enchant. I just like having a Dead Thrall following me as a Vamp. Could use Archery buff, but meh, Bows are no fun for me.)
Silver Ring - One-Handed Attacks and Sneaking. Kinda needed.
Vampire Armor - Illusion and Illusion+Magicka. I like to abuse Invisibility to disengage combat and it helps a lot with Harmony.
Vampire Boots - One-Handed Attacks and Sneaking. Because if I can be Invisible without Invisibility, I'm happy.
Ancient Shrouded Gloves (Legendary) - Double Sneak Attack
Dragonbone Dagger - Fire and paralyze
Dragonbone Sword -
(Optionnal) Mehrunes Razor - When you just have faith in RNG.
No Helm club. Cause hats are ugly. If I had a non-unique helm/hat, enchant-wise... Archery/Magicka and Water-Breathing ? It doesn't matter anyway. Diadem of the Savant can be useful if you like casting things. I always have my Guild Master Hood for 20% Prices on me when I go shopping. Nightingale Hood, could replace an Illusion enchant on the Torso but I don't know for what except Fortify Light Armor or an Attribute, wich is not really useful anyway. Ancient Shrouded Cowl and Krosis Mask if you think of using a Bow (Always useful against Dragons, but I've already played an Archery character and it was kinda lame and OP, so I usually pop a Thrall and aggro with Destruction Magick. When it lands, Invisibility, my Thrall takes the Aggro, and I brutally backstab.). Miraak Mask for more Magicka, pretty useful. And with a Falmer's Helmet over the Diadem or a Mask, it's ugly, but you can be Enchanted AF.
Still I don't see the point when you already one shot everything. Only the Gloves and the dagger/sword really matter. lol.
And don't forget to abuse the Alchemist/Smithing enchanted set and the Fortify Enchantment and Smithing potions. And only then, you're really a badass mage-vampire-serial-killer.