The Frame of Humiliation

The Frame of Humiliation is for those found unworthy to stain the weapons of the men tasked with killing the man.
'She has accepted me,' said Pa-Kur, 'and will rule by my side.' The stone eyes regarded me, expressionless. 'It was her wish that you die the death of a villain,' he said, 'on the Frame of Humiliation, unworthy to stain our weapons.'
Tarnsman

It is considered sacrilegious to terminate the suffering of one who is on a Frame of Humiliation - men on the frame are villains, betrayers
Of one thing I was certain - there would be no human assistance or even pity, for the poor wretches on the frames are none but villains, betrayers, and blasphemers against the Priest- Kings, and it is a sacrilegious act even to consider terminating the sufferings.
Tarnsman

The frame is hollow, to float on the water (here, on the Vosk river)
Ropes hold the man in place at his ankles and wrists
My wrists and ankles were bound to a hollow, floating frame. The ropes sawed into my flesh as the weight of my body drew on them. I turned my head, sick to my stomach, and threw up into the turbid waters of the Vosk. I blinked my eyes against the hot sun and tried to move my wrists and ankles.
A voice said, 'He's awake.'
Dimly I felt spear butts thrust against the side of the hollow frame, ready to edge it out into the current.
Tarnsman

It is custom that each man spits on the body of the man on the Frame before it is pushed out to the water
Then, each of the men of Pa-Kur, as is the custom before a frame is surrendered to the waters of the Vosk, spit on my body. Lastly, Pa-Kur spit on his hand and then placed his hand on my chest. 'Were it not for the daughter of Marlenus,' said Pa-Kur, his metallic face as placid as the quicksilver behind a mirror, 'I would have slain you honourably. That I swear by the black helmet of my caste.'
'I believe you,' I said, my voice choked, no longer caring if I lived or died.
Tarnsman

Death may occur by exposure and lack of water
Villain may be killed by animals - water lizards, turtles, wild tarn
The death would not be a pleasant one. Bound helplessly, without food or water, my own body would torture me by its weight dragging on the hand and ankle ropes, suspended a few inches above the roiling, muddy surface under the fiery sun.
I knew that I would not, some days hence, reach the delta of the Vosk and the cities in the delta except perhaps as a bound corpse, withered by exposure and the lack of water. Indeed, it was unlikely my body would reach the delta at all. It was far more likely that one of the water lizards of the Vosk or one of the great hook-beaked turtles of the river would seize my body and drag it and the frame under the water, destroying me in the mud below. There was also the chance that a wild tarn might swoop down and feed on the helpless living morsel fastened to that degrading frame. Of one thing I was certain - there would be no human assistance or even pity, for the poor wretches on the frames are none but villains, betrayers, and blasphemers against the Priest- Kings, and it is a sacrilegious act even to consider terminating the sufferings.
Tarnsman