Imago was a term used to refer to a more complicated concept somewhat blended between "resurrection body" and "morphogenetic field". It also was said to have connotations similar to someone's self image, or how the default setting of their body would be, if you were able to undo external manipulations. Academics debated whether the study of it should be classified under archemathics or biodata research.
During Resurrection Day individuals were reborn at varying ages and aged at varying rates, amputees may or may not recover limbs, cyborgization, elective surgery, etc, may or may not have been replicated, and a small proportion of people permanently changed sex. Changes to the personality, be them from trauma or physical damage, seem to stick, however.
The City-Born are similarly invulnerable to obvious harm as all other residents, but lack an immutable imago, it takes them some decades before it sets, as tattoos, cosmetic alteration, etc, all work for them at first. (PROSE: Of the City of the Saved...)