bug or not?
Selling items from inventory (after you click All) will sell even items currently equip on your character.
I think those items should be locked and not be selected for selling option unless you put them into inventory.
This happened to me as well. I sold the pants I was wearing with no warning. Not only that but it seems the item drop rate has drastically dropped so It took forever to find a new set and they are not as good as the ones I accidently sold.
I've seen the option to do this, but by default it asks to sell one, so I never have sold equipment I'm wearing.
If you are unlucky as i am, you end up with the same item 5-6 times in your inventory.
Selling them one by one is really slow.
Having to remember how much you have those items to be able to set the sell number -1 is also not good.
Suggestion: Make character slots to lock your items so you will don't sell those items by accident like me.