Reasons why Dispater must die anyway:
1.
Aspect of Dispater
Rust (Su) If Dispater succeeds on a touch attack, his touch causes the target metal to corrode, falling to pieces and becoming useless immediately. His touch can destroy a 10-foot cube of metal instantly. Magic armor, weapons, and other magic items made of metal must succeed on a DC 36 Reflex save or be dissolved. The save DC is Constitution-based.
A metal weapon that deals damage to Dispater corrodes immediately unless its bearer succeeds on a DC 36 Reflex save. Wooden, stone, and other nonmetallic weapons are unaffected. Dispater can suppress or resume his rusting touch ability as a free action. The save DC is Constitution-based.
I think I have made my case.
You may hear screaming magpies in the backround.