There is no shortage of traditional weapons, such as bows and arrows, swords, spears and an endless variety of guns, lasers etc. When none of these are permitted, you could fabricate and entire armory with nothing more than a roll of graphene tape.
Once graphene is easily producible, it will be possible to buy graphene tape. When I was a child, my friends and I used to make swords by rolling up tape measures and pushing the center through and drawing it out as far as possible to a point. If you roll up graphene tape and draw the center out, the point could be pretty sharp. Being graphene, it could also make a pretty strong rapier.
Also by winding some layers around a triangular cross section cardboard tube (or carbon fiber, or even a piece of scrap paper), a pretty rigid tube would result. Bending and tying the ends with strong graphene string or tape would result in a bow or sword.
The stringed bow would only need very fine string thanks to the huge strength of graphene. This would make a good bow but also make a cutting weapon in it own right. If a layer of tape instead of string were used, the same strength would be available with an even sharper edge.