Do you think it has to do with his soul staying in his body or with his fruit?,
lmao totally did miss this post, sorry brotha
I think it's more due to his fruit and how the One Piece world works.
I think fire is also somehow related to life, that's why alot of fellas have fire imbued abilities.
Ice is connected to the dead and that's why it fits with Brook, who stands for death and return to life.
The fruit probably allowed him to access the nature of those powers. Else Brook would maybe also be a fire user.