We all know that this fight comes down to Shepard vs. Raiden, so let's talk about that.
I know what many of you, particularly Metal Gear Solid fans, are thinking. How could Shepard possibly beat the super-human Raiden? Shepard is a pretty awesome human, but Raiden is super-human. Shepard can't stand up to that. Well, I've got a secret for you; Shepard wins that fight. And I'll show you why.
This is Kai Leng:
He is the most dangerous assassin in the galaxy during the time when Mass Effect is set. Much like Raiden, he's got super strength, super speed, super durability, regenerative shields, all the bells and whistles you would want in your artificially augmented super-human. In the above video, he kicks the ass of the second most dangerous assassin in the galaxy, Thane, an alien who has many of the aforementioned attributes from birth due to his race. Kai Leng defeats him soundly, only using a sword against a blaster. And that's between destroying hover cars that are in mid-flight, punching through metal, and (non-canon) killing Miranda, a very powerful biotic. Oh, and he has Reaper blasters on his palms. Reaper blasters, a handheld version of the weapon that destroys civilisations. In his hands.
Kai Leng is essentially Raiden, except with perhaps more advanced technology implanted in his body because he's a few centuries in the future. He can be kind of a badass.
You know who else is a badass, though? Commander fucking Shepard. Let's watch what happens when Shepard battles Kai Leng:
Spoiler alert, Shepard wins. Not only does he win, he breaks Kai Leng's sword, then essentially guts him. Because, at the end of the day, artificial badassery just can't measure up to natural badassery.