Wielding weapons and armor pieces accidentally

Hi!

I encountered this kind of issue:

I just had cleared The Tower of the Shuttered Eye with friend. While looking for the key I must have accidentally picked up rusty sword from table. I didn't notice that my avatar did automatically wield that sword. Well, at the same time of course my two handed sword of flaming went to my inventory. Because tower was cleared I didn't use my weapon until I did enter Greymark forest. Thing that irritates me a bit is that I did accidentally sold that two handed sword to vendor before Greymark .

I know, I know... silly me. I only blame my self, hurry and couple glasses of wine . But anyway I am wondering why is this even possible? If I have complete set that I always wear and use, in what reason my avatar starts to use things I pick up?

Phew... *starts to grind at mines*

 

If you double klick an item like a sword or shield placed out as decoration you instantly equip it...I think...

 

Yep, that was what happened. Bought new one already and I didn't lost much but I just wonder if this is necessary thing to be in game. Probably yes because it is possible....