If memory serves me right, which it doesn't always.
Duvon used two methods, as he was having trouble with the tight scabbard. He mentioned several times, that his own scabbards were loose, allowing him more flexability.
Cross draw, holding the scabbard with left hand and pulling Khukuri.
Trying to pull Khukuri out with left hand and rotating hand positioning in midair. Tight scabbard wasn't cooperating.