What would you improve? For me, it'd be the combat system and "Boss Fights"... Speaking as a non-magic user, the combat in Skyrim is just too simplistic, and enemies don't pose any real threat as you can just absorb hits while hitting each other over the head with swords/axes/maces, which makes it a bit unsatisfying for me. Not to mention the small selection of weapon types.
And for Boss fights...Well, I'm sure a lot of you were disappointed in the end-quest Alduin showdown. I feel like experiences should be more unique when fighting such major Lore characters, like Mannimarco or Alduin, and not just fighting another mage/dragon with the same move-sets, animations, tactics etc. but with more hp and maybe an extra power.
An example of a good fighting system and Bosses to me would be my beloved Dark/Demon Souls. In even normal battles with grunts you have to keep in mind how they fight, what weapons they're using, and how you approach them, and if you decide to just rush in and try to bash like in Skyrim, you get punished pretty badly.
As for what you have in the system, every weapon you can equip usually has a different moveset (a longsword may have a different moveset than a broadsword etc.) so you can choose your favored fighting style from a wide selection of weapons (whether it be wide crowd-slaying swings or precise stabs, or a combo of both). As well as a more skill-based dodging and parry-and-reposte system.
As for Boss fights almost every boss fight in the Souls series is a unique experience, with each boss having a unique move-set, weakness, and strengths, as well as presenting a real challenge to overcome in a satisfying manner.
Yes, I realize Souls is Souls and Elder Scrolls is Elder Scrolls, but it wouldn't hurt to them to take some ideas from them, or vice-versa (Skyrim certainly has a superior Open World to Dark Souls).
So, what would you improve?