Who is High Priest of Blind Io from Mort and what is their importance?

The High Priest of Blind Io is the doddering cleric in Sto Lat, who is called upon to officiate at Princess Keli's coronation. The High Priest insists upon following the full order of services until he is forcefully convinced to jump straight to the sacrifice. He has become so slow that sacrificial animals wander off in boredom or drop litters, so an arthritic elephant is chosen for the occasion. In the end, the High Priest only manages only to knick its trunk, which causes it to rampage.