Eight buttons represent the hands of the droids.
Clicking a hand with the right mouse button will activate the item used in the hand, if it can be activated. The droid will punch if the hand is empty.
Clicking a hand with the left mouse button will pick up the item in the hand. If there is already something in the hand of the leader (well… your mouse cursor, not the hand button!), the item in the hand icon will be swaped with the item in the hand of the leader.
If the hand is equiped with an item that requires ammunition, a bar will also display the amount of the last 25 ammunitions left. There's a 0.3% chance that a weapon jams, indicated by a red bar. To reset the weapon, you need to reload it with new ammunitions.
One important thing to note is that the location of fired ammunitions from firearms depends on the location of the droid who fires it.
This information is useful when the encounter is, for example, on the right side. You now know that it is useless to use your top-left droid because it won't be able to hit anything.