I love a character who’s badass enough to take on two, three, four enemies at once. And writing that sort of scene is really fun. There are all sorts of ways to make it believable, and lots of places to turn to for how it works. But I want to make one suggestion.
You know what the most unrealistic thing in most war movies is? The wounded to kill ratio. It’s like, every time the hero shoots a bad guy, the bad buy dies. That’s never been accurate. Even in the ancient world, where the lack of medical knowledge drastically increased mortality rates, you hardly ever hear of a battle where the wounded to killed ratio is lower than 3:1. In modern warfare the ratio is significantly higher. So the next time you’ve got your protagonist surrounded by bad guys, why not disable all or most of them instead of killing them? A sword-thrust through the upper thigh, a broken arm, a sharp rap to the head, a punch to the solar plexus. Not only will it feel more believable, but by reducing the body count, you make it more powerful when you actually do kill someone. And more powerful is more gooderful, right?
Just a thought.