Equestrian portrait of Daoguang emperor（1782-1850) by Sheng Zhenlin（沈振麟, 19th Century),The Palace Museum.
I think that the position of the Emperor's dao is depicted higher than usual, probably to emphasis it's presence, but it got me to thinking. Manchu's typically wore their swords in this fashion with the hilt back, edge down, during the Qing period. It is generally believed that the draw was accomplished by the left hand grasping the scabbard from below and rotating the hilt forward into the right hand such that edge was facing up. The dao was then drawn in one smooth action in a downward arc. This is contrast to how the jian appears to be generally drawn, with an upward liao cut. Taking into account being mounted, a fast draw upward cut could easily strike the horses head. Therefore a pi cut that draws upward from the scabbard and cuts down would be favored. This would explain the hilt back position for the slung saber favored by the Manchus.