The corpse of a noble who dies in battle becomes the possession of winning
stack. Optionally there should also be a chance that a dead noble from the
losing side should end up in the possession of that side (maybe according to
the capture rules) or that a noble gets lost in the province and has to be
recovered by explore/exhume.
After 8 months the body decays. There is no restoration of noble points to
the faction. Likewise if the body is used for necromantic experiments. To
recover there are two options.
A priest with the lay to dead skill, in possession of the corpse and inside a
graveyard can finalize the body. When this happens all or almost all noble
points invested in the noble are restored to the owning faction.
Or a priest with the resurrection skill, in possession of the corpse and
inside a temple can cause the noble to come back to life. The noble is
completely restored and remains under the control of his owning faction. The
priests faction however permanently loses one noble point.
On the whole I think this ensures that death is serious and for most
characters irreversible. Most characters will be laid to rest which will be
very useful. Factions may even want to trade corpses after the end of a war
so that both sides can recover. Only a very few high-ranking nobles will be
worth resurrecting and for those the owning faction better be willing to
compensate the priests faction generously.