' Barter' is from Old French 'barater' meaning (guess what?) 'to haggle' ,which dates from the C12 . The word 'barter' is true to its origins ! The words 'barter' and 'haggle' are synonyms.
What distinction in meaning do you make, Captain? That 'barter' means 'to traffic by exchanging one commodity for another, in opposition to purchasing with money'. Well, Dr Johnson gave only that definition in his Dictionary. He defines 'haggle' as 'to be tedious in bargaining; to be long in coming to the price' How would you define 'haggle' ? Not as Dr Johnson did but simply as, say, ' to argue in bargaining', without reference to time ? Well, if not, that goes to show how language evolves, changes over time ( in the case of 'haggle' since 1775). Dr Johnson thought of slowness, we don't.