Does anyone have tips for a purely sword and board / two-hander player against casters? I usually hide outside line of sight till they get close then whack them.

Fire isn't so bad because I can dodge the fireballs as I charge toward them.

But shock hurts a lot and I can't dodge it. Am I supposed to use the shield spell against it? I would prefer to not use spells because my character is a nord.

I also have difficulty getting close to frost users that slow you down. Usually it's a boss wizard that backpedals while smothering you with frost.

And what about atronach summoners? Should I kill the atronach first or should I kill the summoner? What if the summoner is a boss with lots of health?

Well they are usually rather soft wearing no armor usually. I often pick them off with a bow from range or just rush headlong in and crush them with brute force. Wearing armor that has magic resistance enchantment is not a bad idea. Or weapons that are enchanted with magic drain.

Wuld or Fiem can be used to close the distance between Our character and the Pesky Mage.

Venison Stew has a slow Restore Health and Stamina effect, Power Attacks and Sprints to close Gaps become much more survivable.

Ever stepped on a Rune? Imagine what a Rune does to a cowardly Mage backing away from Our character. A Cloak Spell can be an effective tool for a clever Warrior.

A Smart Warrior knows killing the Summoner also kills the Summon.

Shock is used to deplete magicka, and then health. Use a good shield that has resistance on it, and use a good bow and get them or wound them from a distance. If using a 2-handed weapon, use resistance on your clothing. Bashing is great on a mage weather using shield and sword or 2-handed.

Although to tell you the truth, no warrior has ever bested this sorceress yet. Only dragons and dragon priests have that honor.

I play 2-Handed melee. I've never played sword-and-board but I'm sure the same principles apply.

I use the terrain to my advantage. I hide behind rocks, buildings, anything that will shield me. I step out from behind, draw fire, and quickly dart back before the spell connects. I keep doing this until the mage runs out of magicka. When mages run out of magicka they will often draw a dagger and run towards you. At this point the mage is already dead. He just doesn't know it yet.

If I think a mage might be present up ahead I scout the area. I look for cover, I try to anticipate where a mage might run, how he might try to attack. I plan an escape route in case things go bad. Strategizing before a battle with mages is worth every bit of the effort, I have found, when playing a melee character.

I usually bring a follower to distract the Mage or like Resy said, use a bow.

Abuse the elemental resistance block perk, have a shield with good resistance enchantments, or as said above, have some sort of ranged weapon on hand.