Just because player A knows more about fighting in real life than player B, that doesn't mean player A's character is a better fighter than player B's.
After all, when you throw in the different races and such, how much super detailed RL fighting knowledge actually translates to PlaneShift? Sure, if you have two Ylian fighting you can imagine it like a real life fight, but what about kran, or kylros, or enkis? Surely moves/grapples/holds that would work against real people would be totally ineffective against them and vice versa, since their bodies are shaped differently and move differently.
The point is, requiring players to have deep knowledge of RL fighting is unnecessary. It's a game. It's not a simulator. All that should be required is common sense and the ability to envision actions in three dimensions. On that note, the more specific you are about what your character is doing, the easier it will be for everyone to envision the same thing.