Well, i guess we are not really getting any closer to the original intent of the passio sumange, though Andi has some interesting things to say here.
http://www.vikingsword.com/vb/showthread.php?p=99317
I'm not sure that Jean's hanging suggestion make sense since many of what appear to be earlier examples or not the simple cord variety that his or Rasjid's keris show. Also, the loop is on the front face of the sheath so i cannot see how it would hang well from a belt with this loop.