It's a strange rule to lost a big item only because you are throwing it inside a room and you can pick it up from the floor later, but I would not risk to lost an artifact like the Axe of Destruction by throwing it!
I would not even allow it to be thrown because it is a special item. Its blows are uncommon so I don't think you can throw it. Also it looks bigger and more heavy than a standard hand axe in my opinion.
Agree with the rule that minor (single use) artifacts like Magical Throwing Daggers should not be useful to recharge the Axe or every dagger will result in a 10 dice attack.
Another thing I would like to change is the Chaotic Sword! I would remove the minimum number of 2 dice attack. If you roll a
you will only attack with 1 combat die. I like the possibility of this unexpected negative event; it's a Chaos sword, somehow it should have a negative side too!!