Eventually everything would become common weapons. There used to be a time when a pen was a unique weapon (not in the literary sense), but more and more fiction, such as James Bond made the pen become some kind of hidden weapon. So people now get bored with a pen weapon. So people look for other things, which hasn't been done yet, but it will also eventually be common.
There was a time when the kris, the kukri and the shawl were uncommon weapons, but now everyone knows them. Ai-chan suppose the only things that you can consider uncommon weapons are weapons do not carry on you, but grabbed from the environment, such as rocks, fallen branches, broken doors, roof tiles, salted fish.
Funny enough, a large, thin scaly fish, when splayed open and dried, is a very effective and light shield, if you do not remove the scales. It provides good protection against arrows, though higher power ranged weapons of above 50 pounds draw weight could still penetrate it at medium range.