This is very interesting concept art. Mostly because it's in no way similar to to the cover art I've seen. It's refreshingly different. I love that sword. I've always loved the leaf-like curves on weapons. I like how this is inspired by weapons like I've already seen (mostly LotR concept for elvish things), but is a creature of it's own. I like that it seems more alive because the Charter is supposed to be a living power and Abhorsen's sword does seem to have a life of it's own. The bandolier seems more practical. Making each case more like a standard sheath, sliding out from the top instead of the bottom, just makes sense to me because it would be easier to still the bell tongue while taking it out and easier to take it out in general - at least for me. I like how the curving leaf concept is reflected in the bells as well, it gives a sense of symmetry of Charter life between tools. I'm honestly not sure about the cloak. While I enjoy how pretty it is and how it accentuates the curves on the Abhorsen, it seems too pretty - this is something an Abhorsen needs to fight terrible things. They has to be able to move. I love that front gold piece - I might be off the mark, but I think you threw in free magic creatures and some dead in there. I can certainly see what looks like a Stilken in there (praying mantis hooks). The cloak's color is definitely Abhorsen, but the silver keys emblem that's on it isn't obviously Adhorsen and it sort of has to be if the bells are showing. If the bells are showing and it's not clear that they're are the Abhorsen, people will think she's a common necromancer and pretty much fight her at every turn, or run away, etc... Having the silver keys emblem more obvious averts that.
Anyways, now that you're done reading my small book of commentary, make more art! Wee!
Interesting interpretation of the sword. Most people would imagine it as a double-handed or broadsword. But, now that I think about it, I don't remember if Garth Nix ever described what type of sword...(checks the book)...yeah, it's a sword with a cross-guard. But I still love the interpretation. Always think outside the box & let your imagination take you where it will.