I was crawling the Internet to find out what the functional earth found on some RCBOs was for and stumbled across the following video that explained it along with a full teardown of how everything works, a demo of the bimetallic strip and arc arrestor in action before then finally overloading it to destruction:

https://www.youtube.com/watch?v=gOUSDDLKICk

Thought it might be of interest to others!