The Life after death is not very good for normal troops - you just get soulless which aren't very useful.
But that is a big perk on mages - Pythium Arch Theurgs cost 380 to make, and one arrow and they die usually. But this way, they turn into soulless with all their magic intact(!). So you have to kill them twice to really lose them.
I like them better as soulless - no longer have to pay income on them
I imagine a goal will be to get consistent ways to have the blessed mages converted to soulless to save on income - maybe the life leeching spells that target troops around you?