"Natural Defense" - the ability of a role to survive an attack directed at it. The following roles have it: King, Royal Guard, Paladin, Seductress, Outcast.
The Nameless One ignores this defense.
The hint about the Assassin is given only on the second night and only if his target is dead.
The two properties of the "Perfect Combat Training" ability are independent of each other. That is, when attacking a member of the Royal Guard, he can: survive and kill the attacker; survive but not kill the attacker; not survive but kill the attacker; not survive and not kill the attacker.
The Angel of Retribution sees no difference between those who committed the murder. This means that she can kill both the murderer who committed intentional murder and, for example, a guard who killed while defending.
"Retribution" does not work on those whose murder failed (block/defense/healing). The Assassin becomes vulnerable to it only after his target dies from poison.