Here's as close the the official word as you're likely to get, and it doesn't really answer your question!

(From the Glorantha Lore Tumbler, as scholarly a site as exists:) http://glorantha.tumblr.com/post/97086371942/tell-us-of-ghosts-and-spirits-lawspeaker

In Glorantha, everything has a spirit. There are spirits for everything in nature; every tree, every stone, every animal, every human and everything else. Your spirit is what animates you and gives you life. It has many different names: your breath, your heat, your shadow, your beast soul. Without your spirit, you are not alive.

it concludes with:

Ghosts are a bit trickier to define. Like I said before, there are spirits of the dead who are restless and dangerous to the living. But there are also ancestor spirits, who are worshipped by many cultures and are entirely benign. And there’s ghosts in the Underworld, where dead spirits are meant to go. Either way they’re a type of spirit, but it’s pretty situational, like many things in Glorantha.

And there you have Glorantha in a nutshell!

Here's as close the the official word as you're likely to get, and it doesn't really answer your question!

From the Glorantha Lore Tumbler, as scholarly a site as exists:

In Glorantha, everything has a spirit. There are spirits for everything in nature; every tree, every stone, every animal, every human and everything else. Your spirit is what animates you and gives you life. It has many different names: your breath, your heat, your shadow, your beast soul. Without your spirit, you are not alive.

it concludes with:

Ghosts are a bit trickier to define. Like I said before, there are spirits of the dead who are restless and dangerous to the living. But there are also ancestor spirits, who are worshipped by many cultures and are entirely benign. And there’s ghosts in the Underworld, where dead spirits are meant to go. Either way they’re a type of spirit, but it’s pretty situational, like many things in Glorantha.

And there you have Glorantha in a nutshell!