What do you think is the narrative, thematic and symbolic relevance of Claudia's amputation and prosthesis?
There's a few, I think, both in how the actual amputation happened, and then how the show handles things with her actual prosthetic.
The amputation:
Claudia is drinking and using a spell that uses her own blood. In arc 2, she increasingly takes on more animalistic forms with her dark magic (snake spell, wings, the tentacles). This mirrors how she's increasingly cannibalizing herself and treating herself as spell parts, as well as themes of fragmentation ("How are we going to move it?" "In pieces" / "We're all that's left of our family, and I'm not going to let anything break us apart" / "Our family was shattered forever"). She may not realize that's what she's doing with herself - dark magic is an extension of herself and her power - but that is what she's doing, hence having a 'dark magic leg' cut off but with real lasting consequences.
There's also the element of Rayla and her brutality that comes into play. Rayla nearly lost a hand in trying to save Zym and usher in peace, which is why she got to - narratively and literally - keep it. Meanwhile Claudia is going down an increasingly dark path, so she loses it, just as her assault on Ibis led her to injure her leg with her dark magic flask. That's not to say becoming disabled is a narrative punishment, but it does showcase how she's putting herself in 1) increasingly dangerous situations for 2) increasingly dangerous people and 3) always by herself. This is contrasted by how the trio wins because they have each other VS Terry (+ Claudia's support system) being regulated to the shore.
Rayla in arc 2 is walking her usual razor's edge of on the one hand being increasingly open and empathetic / letting her compassion shine through - which is a good thing - while being hands down more violent than she was in arc 1. She left to hunt down Viren and recognized it'd gotten twisted into revenge, much like her first mission, and gave this one up without a dragon's egg to change her; she held Terry hostage (although whether she would've hurt him is unknown, but the threat was there!), abandons the drake when Soren doesn't, and cuts off Claudia's leg, etc. We even see this with her actually agreeing to kill Callum if he's possessed again (6x03). All this is, I think, there to create room for the possession plot line to take centre stage in S7 as her own 'dark path' as an assassin will be challenged and likely, finally, put entirely to rest. (Arc 2 opening with her failing to kill a high mage and it's a bad thing vs closing with her failing/refusing to kill a high mage and it's a good thing, probably?) And Claudia represents like the middle road of Viren and Callum in some ways, just as Callum is a middle road between Viren and Claudia -- but meta for another day maybe
On a plot level: it's much harder for Claudia to stop and keep up with Viren if she can't fully walk, and it represents how she's continually sacrificed herself and her body for her family's survival (which dark magic is deeply interested in the idea of "bodies as sites of trauma" but again, meta for another day maybe / adjacent metas in my 'dark magic' tag).
As for her prosthetic:
Claudia has always used magic as a crutch, specifically dark magic. She doesn't have to deal with the big scary feelings permanent consequences or 'brokenness' can bring if she can fix it with dark magic. She can "cure" Soren and bring her dad back from the dead, and she expresses confusion or mistrust when those experiences of being paralyzed or dead undoubtedly affect them and change them, especially when it changes in ways that take them away from her. Because if they're not okay, or not here, then she's not okay. Her using her corrupted Sunforge staff, which at this point just represents dark magic in her life tbh, as a literal crutch is what she's been doing emotionally for a while now, which is also why she takes it with her when she leaves Terry. (The fact that it, much like Claudia, is a corrupted light is just the symbolic cherry on top.)
This isn't too dissimilar in terms of framing of how Callum uses magic as a crutch to distract from / avoid his emotions in S4, and how he drops the staff in order to pick up Rayla's sword to embrace those feelings and embrace her. And why Claudia has a moment of likewise dropping her staff to embrace Terry as well; even if he isn't as critical of dark magic as he arguably could/should be, he is still one of Claudia's guiding lights and wants what's best for her.
