During the time of Queen Elspeth the Peacemaker, there was a small chapel in Companion's Field. It had a bell tower standing next to it. At the time it was built, a bell was installed, but it had no clapper as yet. Immediately after, a Herald died, and that was the first time the clapper-less bell rang. In present-day Valdemar, the chapel is long gone, but the bell tower remains.
It may also rung when Heraldic trainees die.
The Death Bell rang when Tylendel died, shortly after he was repudiated by his Companion, Gala. This was widely perceived as a sign that Tylendel was forgiven for his actions, and was the reason he was buried in Heraldic Whites, with the honors of a full Herald.