A large part of the problem is how to identify sellers, and yet keep it simple Alan had a good suggestion: Just ask them!
I also think that perhaps it would be prudent to develop a line of pertinant questions which have to be answered as people register to join the forum, and with this perhaps stop potentially new members from abusing the rules.
As it is presently, all a new prospective member have to do is to select a username, password and email address.
Perhaps a format that include a form with questions to the prospective member is in order. One of those questions of cause would be, Are you a dealer? yes__ no__, Do you regularly deal in edged weapons? yes__ no__ , Are you a collector of edged weapons who only deal in order to enhance your own collection?yes__ no__, etc. etc. etc. etc.
It is my belief that prevention is a powerful tool, and if the questionere is molded correctly, a great deal of the existing problems could be avoided.
Just a suggestion