Hi Charles. I'm very short on time right now (preparing for yet another hurricane
), but I'll give you my initial impressions.
I believe the first one is Burman. That carved, pierced handle work has become familiar. The scabbard is unusual, but not unknown. I believe Ian has a very similar scabbard with a rounded chape.
I'd say the bottom one is Thai.
The middle example is, as you note, the most puzzling. I agree with the Laos/Vietnam feel to the handle. We've discussed several Laotian dha with similar handles, as well as the Vietnamese Kochin Sabers Philip presented at Timonium. The scabbard and blade look Thai to me.
I'll try to come back with more later. Nice swords, thanks for sharing!