So all I can remember is that it’s set in modern times. Both humans and demons can sparr with each other but the demons have to wear a special bracelet to reduce the amount of power they have. There’s a couple of scene I remember. Kagome was at Sesshomaru house with his family for dinner and she challenged him to a duel but he refused because there was a possibility that he might claim her. I think Naraku was invited over to or something like that. I think there was also a scene in which she was attacked while she went out clubbing with Sango.

I believe you are looking for The Pact by Nenyanna. It's rated M on FFN so to be safe I'd say it's rated MA here so no YIMs.

www.fanfiction.net/s/12033665/1/The-Pact