Ok hear me out… we discover how to make a really fine, really durable but also lightweight metal that can withstand modern bullets. Then we get a really strong, fast, resilient guy in an armor made of that metal and put running stilts on him. Then we give him a longsword and deploy him in a war zone.
Can you imagine being a terrorist soldier and seeing a 6.5ft tall man in a full suit of armor running at you at 15mph with a sword?