Daegal is a fan favorite but I never said he would last more than one episode... He deserved so much better and him as Merlin's apprentice would have been such a cool thing (you're not the first reactor to say that by the way). Yes he dies, but he's among the fandom one of the favorite one off characters on the show. I suppose anyone who plays alongside Colin can get that love from the fandom because he has chemistry with evryone and he makes any character that has scenes with him likeable (Freya is also a good exemple of that). Even the director of this episode mentioned it in the comment.
Daegal, even though he starts off by betraying Merlin, manages to really pull the viewer in with his kindness and redemption in the second half of the episode. It's really sad how he just dies when he finally started to show how good he could be as a man but also as a secondary character on the show. I wish he had been introduced earlier, then maybe he wouldn't have been killed off right away.
I also love how despite not knowing that much about him, you feel like he's been persecuted his entire life and it's the first time he meets someone who cares and who is kind to him. Morgana probably didn't treat him well and only offered him money, compared to that, there's Merlin, who has no reason to help him but does, but also, who brings him food, tends to his wounds and tells him that he matters. It's no wonder that in the end Daegal decided to help the man who showed him kindness instead of just obeying Morgana. She really underestimated Merlin's kindness in this episode (but it's been years and she's probably forgot about that side of Merlin).
I agree, Morgana using poison to kill Merlin doesn't make sense if she wants him dead for good, because as you mentioned, poisons have antidotes, and Merlin has been Gaius' apprentice for years so he is bound to figure out the cure. But at the same time, I think she's making this personal, because Merlin once used poison on her and so it's her prefered weapon to kill him as well. That poison though seemed to have been quite effective, it weakened him so much that he couldn't even use his magic anymore. Also, Morgana doesn't know that Merlin has magic and is so much more powerful than just a servant boy. Maybe that poison would have killed anyone ordinary within hours but since Merlin isn't ordinary, he survived it much longer. Also, and that's quite the trope in the show since the beginning, Merlin is really hard to kill when you think about it, and at this point, I'm not sure a sword to the heart would be enough. After all he survived many lethal attacks in the past that should have surely killed him. His magic is quite powerful after all, and must shield him from things that surely would have killed any ordinary person.
The Sarrum, contrary to Daegal, is one of the most hated characters on the show. He's even worse than Uther... He's almost too dark for this show in my opinion. When he talks about how he kept Morgana like an animal and the dragon... just horrible. I really feel sad for Morgana that she had to go through that for two years. It's no wonder she's so much more unhinged this season, she's been through quite the trauma and it definitely changed her even more than the earlier seasons. Sometimes, I wish we'd have episodes from her point of view, it would be so interesting to see. And I agree, they should have shown that escape as the intro of the season, it would have set such a darker tone fo the reste of the season and it would have worked perfectly for why Morgana is just so unhinged in that season opener (yep, I'm talking about her wanting Arthur's head on a pike and crows feasting on his eyes...., even Mordred was shocked by that...).
Seeing her suffering so much, also really works with how and why she wanted Gwen on her side. As I said in episode 6, it's completely twisted but I think in a way, Morgana missed Gwen's friendship and feels completely alone, especially after Mordred's betrayal. She's also weirdly affectionate and tender with Gwen and in her own twisted mind, that's what friendship is to her. Yes she is controlling Gwen and it's all a lie, but she's not alone anymore and that's really sad when you stop and think about it. Morgana's been so alone for so long. After losing Morgause, she hasn't really had anyone she cared about and who made her feel loved. Aggravaine was just a pawn to her, even though he cared about her, she clearly didn't return his feelings. I just can't help but feel really sad for her...
On a lighter note, Arthur is just completely lost without his Merlin XD There's a 15 minutes long video of scenes with Arthur trying to cope without Merlin and half of the video comes from this episode XD He's such a mess and we love to see it. Yep, it makes him look completely ridiculous and not very kingly, but Bradley's acting is just so adorable and funny that we can't help but love it despite how ridiculous it is :D
Merlin saying that Arthur won't even notice he's gone... Merlin, have you even been paying attention to how much your man depends on you ? XD And of course, that scene is immediately followed with Arthur looking for Merlin XD I also love how, they only have 2 scenes together but this episode still has so much Merthur content XD We just live for Arthur being worried about Merlin, wanting him back (and saying that to his wife no less XD) and then acting a bit jealous about Merlin seeing a girl. Also how chheky was it of the writer to have Arthur ask Merlin why he was walking with a limp ? This show just doesn't care anymore with the subtext XD it's just too good XD
The scenes between Arthur and Gaius are also really fun to watch. First we have Arthur looking for Merlin and even checking behind the door (that's where Merlin was hiding in 4x03 when Arthur was also looking for him). Then Gaius trying to make excuses for Merlin's absence but Arthur just concluding he's at the tavern again XD
Then the whole scene when Gaius helps Arthur to get dressed XD Oh my XD Such a ridiculous scene but so funny that it just works. What makes it even funnier, is that we know (as viewers) that Arthur knows how to dress himself, after all, how many times Merlin was surprised to find his Prince/ King already dressed. And having Arthur insist that he needs Merlin to get dressed to anyone else but Merlin, is just too funny.
I alos like the more serious scene afterwards when Arthur confesses about his concerns with making an alliance with the Sarrum and Gaius listening and giving him advice. In a way, this scene is really father/son like and I love it.
The comb scene is also really adorable. As you know, I am so not an Arthur/Gwen shipper, but I really love this scene, it's so adorabe and feels really natural. Honnnestly, if they had more scenes like that, I would probably like them more. Also, Bradley totally improvised putting the comb in his hair like that and then looking around completely lost XD
The plotting in the episode isn't really the bast part of it. At this point, I was getting tired of Gwen being eveil and acting completely unlike herself and no one (but Gaius and Merlin) noticing. She's acting so unlike herself around Arthur, it's really a wonder he hasn't figured it out yet. Again, it makes Arthur look stupid for being fooled so easily. Also, Gwen's reaction when the Sarrum gets shot instead of Arthur, just doesn't work at all. She doesn't show any concern for Arthur, like checking if he's injured, she doesn't show shock. But you can clearly read the disappointment on her face and again, it's such a weird reaction to the whole thing.
For me, the best part of the episode is Merlin and Daegal. We get to see Merlin as a mentor figure for this young man and it really suits him. Again, it would have been so great to have Daegal become his apprentice. We also get to see how much Merlin has learnt thanks to Gaius and how proud he is of that. He knows he was lucky to have Gaius as his mentor and it's great to see that being mentioned by him. Also, Merlin really is a good physician now, he barely uses his magic in this episode because he has learnt to heal wounds as a physician rather than as a warlock.
And when Merlin eosn't hesitate showing he has magic in front of him was also a great scene. I love how powerful Merlin looks in that scene when he says "I don't need one" and then just flips the guy in the air. As I said many times, it would have been quite interesting to see a dark Merlin arc. Colin could definitely pull it off actingwise.
Completely unrelated to the plot of the episode, but how good does Colin look in this episode ? He's usually more the cute type, but that scene at the beginning when he tells Daegal to get out, as Captain HOLT would say "HOT DAMN!" :D
The dramatic walk at the end XD I love it but it's so over the top at the same time. Also, this episode definitely convinced me that I wanted the Evil Gwen arc to end sooner rather than later. With only so little episodes left in the season, it's hight time we go back to the main arc with Mordred beraly having had any developpement yet....
Next episode, Mordred's back, some old characters come back and something that I think you will definitely not expect happens. I won't say more, but I think you'll enjoy next episode :)