Onto another point, I decided to implement tests on my SCP's potential in a way that hopefully brings it below the Able (or would it be Abel, the original spelling of the biblical Abel?) line yet makes it not a copy of SCP-076-2.
I don't think this works. If the only reason you have those tests are to try and prove that this thing isn't as badly OP as 076, the audience might just get skeptical anyway.
I also added a struck-through Euclid class to correspond to a possibly hostile capture/containment story.
Eh… why? How would a possibly hostile containment story improve this?
I cannot think of a way to tie it to Thaumiel besides being helpful in resolving danger in the Foundation.
Why do you want to write this as a Thaumiel? Fitan' gud humanoids are hard enough to write well, Thaumiels are also hard in general because people will scrutinize them closely.
Incidentally, how many Thaumiel articles have your read? Have you home through the discussion pages too to see what the audience liked about them?
I was thinking of something along the lines of a vow or promise to aid the Foundation, though it seems rather lazy.
Yeah, that's lazy. Why does this entity want to work for the Foundation so much anyway? They're going to be a hell of a lot more suspicous of it, as opposed to, say, the Serpent's Hand that takes everybody in.
Can you suggest any ideas for the above two?
…don't? Your concept here is still fundamentally the same, OTT superhuman with special weaps and random rule-of-cool cool nickname.
I mean, maybe you can talk to some other authors who have pulled off similar ideas in a more realistic manner, to ask them how they write up cool supersoldiers without coming off as cringy or tryhard.
Hey, 
sirpudding, I summon thee. Ia ia.
