Many thanks for the picture... it's Shan (Tai) people who using a kind of very long sword.
However, those Tai warrior may not related to Rakhan (Arracan) chief. It 's not unusual to find one ethnic group 's decoration style on another group 's objects. Many Lanna weapon use Tai decoration style though
I 'm also interested by those guys on the back. The picture res. 's so low that I could not figure out if they are indian or european. Would you mind to show it in higher resolution ?