This was comedy. Admittedly I have done this quest so many times but you got really lucky that Phineas came in to kill Arcano for you. If you notice all others got paralyzed at the start to make it your show. It is a bit confusing and I have trouble doing this without a bit of prep on master. The darn anomalies are deadly. I look forward to doing this with my Rogue Thalmor Agent on his runthrough.
I think the statement "Skyrim is too Easy" is not the right phrase. The one in the description "Skyrim is too easy if you know all the tricks" where tricks mean glitches and easter eggs then I feel it is more accurate.
I personally play on Master from the beginning and limit my use of tricks. I won't use the resto potion bug, I won't use console commands except to fix glitched quests and I don't use the infinite vendor refresh. I normally run pure mage variations and just make money enchanting daggers since it is weight efficient. I try to keep my enchanting with 1.5x of my destruction skill and experiment a bit. I maximize my time spent in the teens and twenties as there are a lot of challenges in those levels. Difficulty levels off in the 30s+.
I could play on Legendary but Legendary really makes Destruction a pain to play with and it becomes unfun and I then react by getting enchanting to 100 and making the gear I need. When I play legandary I also tend to use Illusion more which is fine for a character but limiting RPG wise.