if anything looks remotely "questie" I just store it in my house... (I have Loki's bow, which I found in the troll cave east of Whiterun, I've had it since very early in the game.... its stored in the house..... never used it, but too scared to sell in case its needed later on)
I guess the game has made me somewhat of a hoarder.
you never know when selling an item could break a quest at the moment, so I'm always err'ing on the side of caution
Unfortunately it makes for a very untidy homestead

Now where DID I put that Ebony War-axe ??
Anyone else the same ?