Protests with armed people tend to keep the cops restrained, and they have significantly less injury and death.
The weapons serve as a deterrent. Because bullies think they can win in a melee, but they don't want to be killed, and their targets are showing that capacity.
I don't like it. I wish we could have peaceful protests without the cops going wild. I wish we could have peaceful protests without the clowns who want to freak out starting fires and robbing stores.
But humans are what they are, and those risks are there.