really cool style! It suits the crumbly, decrepit state of modern Lordran, too. My only gripe would be that if this is supposed to be an earlier portrait, Artie's gear should probably look more intact than it does in-game (where it's been tattered and fouled for who knows how long). Would've been neat to see you get a little creative with what his armor would've looked like in its prime - it's basically the Silver Knight set, but the extra tabards and whatnot would still be interesting. Sif also looks a bit off to my eyes, almost a bit rodent-like in the face, but nothing too bad. Also might've been cool to include Alvina in there too.
I had to draw Sif a little different than I usually draw wolves (which I found a challenge). In the game, his eyes seem small and close together to me, so I did my best to adapt it into my style. As for the earlier portrait thing, it would take place during Artorias of the Abyss in the timeline, so Sif would still be small, though Artorias had already been consumed by the Dark. At least, that's the explanation I'd give. I don't know that it's meant to be an "early portrait", just an image inspired by the game.
Glad you like it though!