The Wall Staples are an item of Duster's. When you use these items, the enemy that they are used on will either freeze or dodge them.
The Wall Staples is one of the 6 Thief Tools. Somehow, Wess obtains them and hides all of them in his basement. When you are first starting your journey with Duster, he will go and obtain all of them. The Wall Staples are the only items that he will use on the map as well, and not just in battle.
The Wall Staples can be used in battle to make an enemy stop moving. This generally will happen for three turns. During this time, they cannot heal with an item, guard, or attack you. These will usually miss, but on certain enemies, this is the only thing that can get them to stop moving, such as the Clayman and the Forlorn Junk Heap. Other times, these items don't work at all. These can also be used outside of battle to scale walls and such. He uses them many times throughout the game, and somehow has them when you first see him.
These Wall Staples only appear with Duster in Mother 3.