This is not a Tank. This is a Mage, but the classic dogma of MMOs is "You can't use a Shield, you're a Mage."
Well, recently [Z]enimax changed the Ice Staff so you can taunt with it, and Block using Magicka. Even before that, there was no reason, whatsoever that a Magicka spec couldn't use the 1H&Shield tree. So, first the FAQ:
"Why would a Mage want to use a Shield?"
Well, first of all, because the classic Mage (Not counting Gandalf, who Tanked a Balrog) is a Glass Cannon. So, the obvious answer is to Reinforce the Glass. If you don't like Dying, but you do like Destruction, then adding a Shield doesn't hurt, when it comes to the Not Dying part. Also, Blocking with a Shield takes Stamina, which doesn't take from the Resource you use to cast Spells.
Next, you come to the mechanics of Equipment in ESO, and a Shield is Apparel. Which means you can Enchant it with a Magicka Glyph, and have more Max Magicka than someone who just has 7 Max Magicka Glyphs. More Max Magicka makes you a better Mage, but beyond that, you can also get 1 more Set Bonus, albeit temporarily.
You get 8 slots for Apparel (Head, Shoulders, Chest, Arms, Shield, Waist, Legs, and Feet.) 2 Weapon slots (Staff, and Dagger. Or whatever, i use a Dagger, but 1H&S doesn't care whether it's an Ax, Hammer or Sword) 3 Jewelry Slots (Neck, and 2 Rings) for a grand total of 13 pieces. However, when you swap Weapons, you either have 11 or 12 Active at any given time, as far as your Set Bonus is concerned. So, you can have a 3 Set Bonus (Vampire's Cloak) with the Dagger, and Shield to get the 4, and 5 set bonus, and a 5 set bonus that's always active, (I have Torug's Pact) plus a 2-3 Set Bonus, the 3rd Bonus toggles off with the Staff. (Right now it's Necropotence, which is a Summoner's set, but as I never get the 5 piece bonus, where it says "When you have a pet active" is moot. It's just More Max Magicka.)
Now, the 1H&Shiekd abilities I like on the Back Bar:
Pierce Armor: Major Fracture from Stamina. This is a Dragon Knight, which means Burn, Burn, Burn, and a little more Burn. When i first made this build, Dunmer had bonus to Fire Damage, as well as Resistance. That's changed to Weapon, and Spell Damage, but it still stands, you can cast Weakness to Elements, or you can save Magicka, poke them, and use Stamina instead. (It also Taunts, so be careful who you poke with that thing.) That saves Magicka you can use to Burn them, while their Spell Resistance is Nerfed.
Shielded Assault: One thing Dragon Knights don't have a whole lot of is Mobility. This comes with an automatic Stun, a handy little Damage Shield, and now it's Spamable! So, that guy you just taunted to pierce his Armor? Yeah, now he's Stunned, and you have a Damage Shield.
Heroic Slash: None of these effects, like Minor Heroism scale with Stamina, nor Magicka. That's what this is: A back Bar, with Utilities, which are nice for a Mage. Ultimate generation from Spamina? That's useful for a Mage. Also, Minor Maim, so you take less damage when they get up from that Stun you just put on them.
Absorb Magic: Says it right on the Tin, but this is also a Slotted Passive, so you can block more fro less Stamina.
Empowering Bash: I don't really like Reverb, because I Kill Healers First. This Empowers your next Bash when you Block. Yes, it scales off of Stamina, and you don't have much (Dunmer have a bonus, but you don't invest in it.) I don't think this is very good for this particular character, but as a Dunmer, you can always respec to Stamina, and switch to Dual Wield instead of a Staff.
Destruction (Staff)
This is a Destruction Mage, however being a Dragon Knight, you've got Fire Magic down pat. So, for your primary weapon, you can Tank with an Ice Staff, or kill them en mass with a Lightning Staff. I went with the Lightning Staff, because it has a passive Bonus to AoE damage, (Which stacks on World in Ruin) and it's not just for Destruction Staff spells. This also boosts your Engulfing Flames, which also makes enemies more susceptible to Fire attacks, especially if they already have Major Breach (And a taunt) on them.
Unstable Wall of Storms sets Concussed enemies Off Balance. This doesn't look too good on paper, but Lightning Staff (With a Flame Enchantment, also remember Torug's Pact) also Concusses enemies on a Power Attack, and oh look, Molten Whip. Also puts enemies Off balance if they're Stunned, and also stacks up to 3 Seething Fury buffs to increase their damage (Weakened by Major fracture, and Engulfing Flames.)
Firey Grip grants Major Expedition, but more importantly, sucks people back into your AoE where you can keep burning them, shocking, stunning, and setting them OFF Balance, Puncturing, and stacking up those Seething Flames to Whip them into Submission.
Burning Embers: A good swipe, with a Dot, and a Heal. Also stacks up those Seething Flames Tokens, and exploits the 2 biffs to their Fire/Spell Resistance.
IDK about you, but I saw a lot of potential rotations right there, and I'm not done yet. However, I don't play a Melee Mage for a DPS, nor a Tank Rotation, I use Animation Cancelling to run Combos. That's what this is, a Melee Mage. A guy with a Staff, a Dagger, and a Shield that's comfortable in a Moshpit, because you have the CC, and a good enough Block to survive there. That means Reacting to the Status of the enemies, and Changing it. Not getting set in a Rotation, which makes for a Fun Playstyle for me. This is a Fight, with fire magic. Not keeping a bunch of Statuses up, rinse repeat until the fight is over. it's bashing to Interrupt, and getting a Cast in there, with an attack woven in for a 3 hit combo that lands all at once, and applies 3 different Status effects, then moving onto the next Target while that one keeps burning...
Utility (Spellbook)
That leaves a few slots, so now back to the Utility side of the swap:
Obsidian Shard: Ranged Knockdown, with a Heal. I love spells like this, because it doesn't do 1 thing, it also triggers Mountain's Blessing, and Helping Hands, giving you, and your Allies Major Brutality, Stamina, and more Ultimate generation. Not a bad way to start a fight, and it's also an Emergency Heal.
Burning Talons: Root, AoDoT, and a Synergy opportunity for your allies. Another one of those multi purpose utility Spells.
Volatile Armor: An AoE burst that hits everyone in the Talons, and also returns damage to enemies hitting you in the Melee.
Coagulated Blood: Just a really good Self Heal. One of the best in the game.
