Server for duels

Hi.
I create a game where players can compete with each other in 1v1 competetive system. (like Hearthstone etc.)
I really don’t want to make dedicated servers, I want to make only listen server on the side of one of the players.
The question is - Is there a way to do it safely?
I mean about Authority problem where one of the players will be a server and he’ll have access to do some advanced stuff which is a big problem.
How to solve this?
Any suggestions?
ps. This will be game with Steam Subsystem if it changes something.

Thanks.
[sorry for my English]