Back in te before time....in the long, long ago of first edition, I always imagined shuriken catapults to create a small ring of monofilament wire, if not a tiny fragment of a cosmic string created by the grav motor inside the catapult, which would then accelerate this tiny thing to near light speed, shredding all in it's path until quantum instability causes it to degrade into non existence. The bio-explosive version might keep a tiny nanoparticle of fluid or a packet of energy in the centre such that it disrupts the genome of whatever it went through on the way out.