Originally Posted By: JIM
IIRC That's why you need to give a silver coin back to the person who you get the knife from. 'so that the knife doesn't cut friendship'


Yes, that's an old tradition. Something to do with the old formalities around duelling, perhaps? To offer someone a sword/knife is to challenge them to single combat. But if a token amount of money is exchanged for the blade, it is symbolically a transaction, not a challenge. (Wish I could find an authoritative reference regarding this.)