I can honestly say that I don't understand that sentence. It appears to be the explanation of a game. Beyond that, however, it doesn't make much sense to me. The "second" may be a technical term just used for the game. Do you know what the game is? If so you can look up the definition online. For example: "Flush poker definition" since the word "flush" has a different definition in poker from its real life definition.

Can you give some context? Perhaps the sentences that come before and after it?

They are talking about a duel, I think. In a duel, each dueller has a 'second' - that is a person that acts as their supporter. Since a duel involves a dispute that is 'worth dying for', it is unlikely that the duellers would be talking to each other - hence why he is talking to his opponent's second.