Okay, I'm going to start by saying this game has been extremely easy for me from 1-35. I've even been farming a dungeon with level 37 monsters for fun. The only times I've died is when a group of enemies sneaks up behind me when I'm out of Magicka or I stupidly jumped from a cliff thinking I'd survive... and evidently didn't.
Might be slight spoilers, but if you've done it then... yeah...
However, then I reached level 35 and got the Valley of Blades quest. I got to Titan and everything went to sh-. I'm not entirely sure if there was something I was supposed to do that I missed, or a bug of some kind but I'll explain what happened and hopefully someone might be able to explain why I had so much trouble.
My gear/stats and build (you can skip the Italics):
All armor Light Armor, all Blue items at level 34 (crafted and improved myself, so higher base stats) and all enchanted with Magicka.
Both Flame Destruction Staffs were Blue at level 34 (crafted and improved myself, so higher base stats) with one enchanted with Frost and the other enchanted with Shock. (1 bar has AoE and the other has ST)
My Magicka, Magicka Recovery and Spell Resistance are all soft-capped, as is Armor due to my Spiked Armor skill.
I run a Pyromancer-style Dragonknight, meaning I use Fire almost exlusively.
Plenty of HP, MP and SP potions to repeatedly do this fight for the past hour...
His basic long-ranged attack that I couldn't avoid took about 25% of my HP off and about 10% when I blocked. He would use it constantly so blocking was pointless as I'd run out of Stamina before he was below 90% due to the fact the 3 legendary NPC's I'm with don't seem to do any damage whatsoever. What I had to do was get in close (which is what I usually do since I'm a PB AoE Dragonknight Pyromancer build), which wasn't very effective, either...
Instead of throwing spells at me, he clawed at me more often, which I again had to block. He had 2 attacks that were easily avoidable by walking around him in a circle, even while blocking and 1 attack that I just had to dodge roll out of, but he had a Wall of Elements-style attack that 1-shotted me, even when blocking. My issue with this was that the red-lines to indicate the skill was interrupt-able were there, but I couldn't interrupt it. I could dodge roll but that took more Stamina than I could afford.
He was also immune to pretty much any kind of CC I could use, or was even the slightest bit useful. Rooting/Snaring are pointless since he doesn't move and throws blue fire at me all day and I couldn't stun or interrupt him, nor could I Knockback/Knockdown.
NOT TO MENTION the fact that I had softcapped Armor and Spell Resistance did NOTHING to slow down my death AT ALL.
I ended up defeating him (I just fought him repeatedly until my Ultimate was charged enough) with an unsatisfied relief, only caring that the fight was over. The 3 characters you get sent in with do pretty much nothing. They rarely took agro and never did any damage.
I thought I was done... but nope! I had to protect something from undead that spawned. At first it was 1, which I was too frustrated with the quest so I went cheap and knocked it down repeatedly. After it died 2 more spawned straight away, one being a caster. The caster would always attack me, refusing to attack the 3 NPC's I'm with while a Melee enemy attacked me and dropped a Standard of Might on me every time... With the inability to block any random basic spell attack, I constantly died until, again, I waited for my Ultimate.
Afterwards 3-4 MORE spawned, at which point I decided straight away to wait for Ultimate due to the fact there were 2 casters, yet I still died and had to fight them all 1 at a time, using Ultimate each time...
At one point I thought it might be due to the fact they're resistant to Fire due to being Daedra (they're using fire spells constantly and I know some Daedra are resistant) but switching to my Lightning Staffs didn't do anything different.
So, 2 hours later I was finally done with this quest... Went back to soloing 6 monsters at a time, soloing Group dungeon bosses with ease...
If this is how the game was designed to be, that's fine. I'm not complaining about it. I'm just trying to figure out what I was doing wrong so I can attempt to... not do it again.
TL;DR:
I'm completely baffled at why I struggled so much with this quest. Is there a simply mechanic I'm missing? My gear was well up to date and stats were all softcapped. Same level as the quest and I know how to play my character well enough, not to mention how ridiculously easy this game is until much later. Are the 3 NPC's I'm with supposed to Tank/Heal/do damage? They did none of that. Did they change fights so that knockbacks/knockdowns are necessary? I don't have enough Magicka to repeatedly knockback 3 different enemies. I imagine a Resto Staff would help, but seems bad for the game if having self-heals is needed considering they want you to play how you want to play. I hate using pots yet I had to here...