From what I remember it was a book series and I picked it up from a 2nd hand store in the 1990s. Not sure when it was published.
In the first book a cop? gets pulled into a parallel universe where they use suits of powered armor. These suits protect them and allow them to generate a sword of energy to fight with.
If I remember its set as if it was medieval times and they were kind of like knights.
As a last ditch effort (from the crappy first suit he wore) he was able to fire all the energy out of the palm of his suit and it burned a small hole in his enemy's suit allowing him to win.
If you win, you get the other persons suit of energy.
That's about all I got, anyone got a suggestion?