It may only be 2mm long, but its spider-fu is strong:
They may be small, but Assassin spiders are among the most dangerous spiders on the planet – if you’re another spider, that is. These tiny arachnids in the Archaeidae family are only about 2 mm (less than 1/8 inch) long, but their bizarre fangs and spider-hunting practices have earned them a reputation as the world’s most grotesque spiders. They hunt by stabbing their prey with venom-filled fangs that are attached to the ends of extremely elongated jaws.
Once warriors learn to kill any enemy with a single blow, the only way to improve is to increase the warrior's ability to strike that single blow first. Among the many factors, this involves sacrificing strength for speed, and power for stealth, but by far the most important factor in landing that single deadly blow before an opponent can, is to be able to strike at a greater range. Having a deadly weapon that is even a quarter of an inch longer than your opponent's will almost always ensure your victory, even if all the more traditional factors favor your opponent.