just give them all the old bullet proof vests that aren't ballistic safe anymore... might not stop a round but a knife will NEVER get through one. just give them all the old bullet proof vests that aren't ballistic safe anymore... might not stop a round but a knife will NEVER get through one.er, they cut ballistic vests out with cheap, disposable sissors in the factories. Knife blades go right through them, as do sewing needles.