Did you know about a dupe using the staff of worms and the skull of corruption (kill, resurrect with the staff of worms create a clon with the skull, and when you kill the clon, the weapon falls in the ground as a pickable one) I will try that with the arena stuff
It seems to me that all the other options are well-blocked by Bethesda
Maybe if there are glitchs like the one I posted it is possible...
though, by then you'll be pretty powerful and you won't want to loot the items of guys you fight in there anyways.
But a lot of players do the arena early...and the resist magic 100% shield is good for a medium-high level char