I know that AntiFa was pushing a custom engraved concealable knife.
Everyone attending these rallies should get some Kevlar Sleeves. They are cheap. $20 for a pair. If someone starts slashing, these will prevent or limit cutting. The natural reaction to a blade coming at your is to raise your forearm to protect your face. These sleeves can help stop grievous injury.
Kevlar is good but I am of the opinion that chain mail is better :-)