Severing Continues

In the Spirit World, as you see, the only way that you can get to become a Kyoshi Spirit might be less exciting than you thought it was. There was only one single way that you could become a Kyoshi Spirit was to slay the past Kyoshi Spirit and assume their position. For example, when Hakki was still a fledgling and young spirit, the past Fifth Spirit of Hunting was already weak and on his dying breaths. 

He was frail from the past millennia of him just existing and wandering in the world, that was when Hakki saw him. The two of them immediately knew what was about to happen, they were about to fight against each other.

As when you are a Kyoshi Spirit, you always had to defend your title and honor against some lowly spirits who just wish to take the title away from you. These 'lowly' spirits never actually succeeded that often, but when they did, it was glorious.