Closed Bread changes attack in inventory screen

Attack value (number next to sword) is 31. Grab the bread, value goes to 0. Put bread back in inventory, value goes back to 31.

 

Noticed this actually happens when I pick up anything from my inventory.

 

when you click on anything, it either goes into your hand or your matter manipulator so you can place it without having it on the hotbar.

 

That's because when you click on an item, you are no longer holding your weapon and thus deal no damage. If you have a weapon in hand, it will not be 0.