Three questions
Which units do tend to die very often in your runs
Which FE game does cause you the most deaths? Which lord does die the most?
A few examples by myself:
FE6: Lilina (in the Sacae-route she was doubled by pretty much everyone), Chad (oneshotted by bolting or purge)
FE8: Marisa (somehow I don't pay attention, where I place her; I overrestimate her dodging abilities)
FE9: Rhys (slow and fragile)
FE10: Laura (level one base stats and very tough enemies), Micaiah (in 1-9, resolve doesn't prevent her by getting hit)
FE13: Maribelle (slow and fragile in the beginning), Robin (lunatic + earlygame => cancelled my run after chapter 3)
In general I've some problems to save my healers. Either they get oneshotted, or they get doubled.