Board Thread:General Discussion/@comment-5674726-20150813192004/@comment-5674726-20150813194053

One pet theory of mine: Morgana couldn't be killed by a mortal blade because of a combination of her healing bracelet and Aithusa's magic.

This theory hinges on another theory about how Morgana's healing bracelet functions. It seems very unlikely that the bracelet is good only for blocking Morgana's visions. For one thing, we see Morgause cast a spell on the bracelet and it's only after she has done this that Morgana settles into a restful sleep. For another, the bracelet's power is said to be without equal in the Five Kingdoms and Alator recognised that it held "true power", describing it as a precious gift.

My theory is that its functions are two-fold. Firstly, in the event of the wearer suffering serious harm, it acts as a distress beacon to attract healing magic, possibly with some kind of compulsion to encourage the wielder of said healing magic to use it to save the wearer. Secondly, it stores the magic and, from that point onward, it will be able to heal similar injuries without outside intervention.

When Merlin poisons Morgana in The Fires of Idirsholas, Morgause is able to sense it and comes running. In The Crystal Cave, despite the fact that Merlin is convinced that Morgana is an enemy and a danger, he is determined to heal her, going so far as to use his Dragonlord power to force Kilgharrah to help. Did he do this solely because he couldn't bear to see the others grieve or, unbeknownst to him, was he being influenced by the magic of the healing bracelet, which compelled him to help Morgana? In The Sword in the Stone, Part 2, Morgana is seriously, probably mortally, wounded by a blade. Aithusa shows up to heal her in the nick of time. It seems like a pretty huge coincidence that Aithusa just happened to be in the area, ready and willing to heal Morgana as soon as she came upon her.

Morgana is clearly not immune to being killed by a mortal blade at the end of Season Four. Come Season Five, she can certainly be hurt by a mortal blade, as evidenced when Mordred stabbed her, but she can't be killed.

Merlin healed Morgana of a serious head injury in Season Three. Since then, she has suffered multiple serious head injuries, some of which could easily have killed her, but always recovered quickly.

I'd hazard a guess that, had she tried drinking hemlock at any point after The Fires of Idirsholas, it wouldn't have killed her.