You did a great job! I helped my friend on an Astrid costume this past summer, so I feel a little sentimental whenever I see cosplayers of her, and you pulled it off nicely! I think the only thing that you need to think about is weathering the shoulder armor. It looks very fresh and new currently, but that doesn't really fit. She's a a dragon-fighting viking! She has some battle damage. ALSO, that helps the metal look more real. It's extremely difficult to get a paint that can really replicate the look of metal, so if it's weathered it's like "okay, well of course it wouldn't be shiny it's all old and grungy!"
Also, on the ax, it looks kind of choppy (excuse the pun!) like, you can really see the segmentation in it. This may sound silly, but my friend and I got a really fantastic effect using craft foam Just drew out two pieces , and hot glued them on either side, and to the stick. Then little pieces at the top and bottom to make it a full-sided object, and then painted it. You could easily put a later of craft foam over what you already have and just seal it at the edges, so you won't have the seam-y bits in the center.
Anyway, as I said, great job! you make a really wonderful astrid, and I hope this helped a bit!