I bow to the metallurgist's knowledge of metal, of course, but it seems historically doubtful that fighting men in the medieval or early modern period went to war with bronze swords. For one thing, the disparity between them and their enemies would have been absurd. I am reminded of a poster I saw depicting a bunch of heavily armed U.S. marines with the caption "Rules for a gun fight - bring a gun - bring lots of guns - bring all your friends who have guns." Going into battle with bronze sword would be like going into a modern gunfight with a matchlock. Also, for the rank and file to be armed with bronze weapons, there would have to be an established trade of bronze weapon making to supply them. Is there any evidence for that?

On the other hand, "pointed with the metal brown" is difficult to equate with rusty either. Any border reiver would be unlikely to let even his number two sword get in that state.