How would I make a game like Fencing?

I have tried and tried but never EVER have been able to make a game sorta like fencing. Like a different arena and plate size but I mean really. HOW?! I can make the arena perfectly fine including the plate that the swords do damage on, but have never understood how to script it. And I'm not sure whether I should insert the script into the swords or the arena plate! Please answer.