Sentence:  Vaguely reminiscent of the use of "<WSD>seconds</WSD>" among duelists, this provision required that the two hostile nations stop threatening each other and, instead, to let two appointed countries (their "<WSD>seconds</WSD>") try and solve their difficulties 
Meaning of the word marked with <WSD> tags:  One who supports another in a contest or combat, such as a dueller's assistant.