It is shown that an angel blade can kill a [[reaper]], as demonstrated when [[Crowley]] kills the rogue reaper [[Ajay]] with one of his angel blades.<ref name="eight19">[[8.19 Taxi Driver]]</ref> The Winchesters have also been able to use angel blades to kill reapers<ref name="nine03" /> as well as Castiel.<ref name="twelve09">[[12.09 First Blood]]</ref> At one point, Crowley has a blade melted-down into [[Angel-Killing Bullets|bullets]] for [[Crowley's Gun|a gun]]. As long as the wound is fatal, the bullets work just as well as the blade itself.<ref name="eight21">[[8.21 The Great Escapist]]</ref> The [[Apocalypse World]] [[Bobby Singer (Apocalypse World)|Bobby Singer]] did something similar resulting in bullets and shotgun rounds capable of killing both angels and demons.<ref name="twelve23">[[12.23 All Along the Watchtower]]</ref>
During a fight with Lucifer, Castiel manages to stab him with an angel blade, but Lucifer is completely unharmed. He is similarly unharmed by being shot with a hundred bullets made from melted-down angel blades.<ref name="twelve23" /> Castiel's later attempt to kill a weakened Lucifer with an angel blade to the abdomen likewise failed, but it did cause him harm.<ref name="thirteen12">[[13.12 Various & Sundry Villains]]</ref> However, [[Asmodeus]] believed that an angel blade to the heart could kill Lucifer in his weakened state though this was never tested.<ref name="thirteen13">[[13.13 Devil's Bargain]]</ref> During an encounter with [[Raphael]], Dean and [[Bobby Singer]] attempted to attack the archangel by throwing an angel blade at him, but Raphael caught the blade before it could make contact.<ref name="six22">[[6.22 The Man Who Knew Too Much]]</ref> However, though archangels can't be killed with the blades, they can have their [[grace]] extracted using them like a regular angel.<ref name="thirteen07">[[13.07 War of the Worlds]]</ref><ref name="thirteen21">[[13.21 Beat the Devil]]</ref> An attempt by [[Miriam]] to kill [[Jack Kline]] shows that [[nephilim]] sired by archangels are also immune to angel blades.<ref name="thirteen01">[[13.01 Lost and Found]]</ref>
After absorbing the [[souls]] of [[Purgatory]] and declaring himself the new God, [[Castiel]] became completely immune to angel blades as he was no longer a normal angel.<ref name="six22" /> He regained this weakness after returning the souls to Purgatory and becoming a regular angel again.