The sound effect for repairing items.
I hate those sounds!
That's the only thing that comes to mind. Mods/patches have fixed the other things that annoyed me.
What is awful is the blocking sound. I mean because it's so LOUD! At one time I played with headphones with no volume change in them. My computer's volume was at minimum. All the game's volumes were also next to minimum. But it turned out that no volume slider in the game governed the blocking sound! It remained standard even though the other sounds were much quieter than before. I didn't use a shield very long after every block began to rip my ears off. -_-
Worst feature I think is some menus. Especially the enchantment menu. It took me much time back then to find out how to enchant, even. And I ALWAYS forget something! Either I don't remember to rename the item I'm creating, or I forget to change Cast On Use into Constant Effect, or something like that. :I Maybe that's just me, though.