I like it, there's great detail on the design, and the colours all fit well. I know nothing about xenoblade, so maybe it comes from the games, but I have a few quips about the clothing design and some other things. As far as I can see, the clothing from the "Is only there to look cool" syndrome. Of course the sword suffers from it, with all the holes, but cool swords are always a good thing. The leg things, though, what purpose do they serve? They're not identical and support the each leg differently, so I'm assuming it has something to do with the God Slayer having bad ankles? I find it also weird that his left trouserpipe has sharp things sticking out, and his left not. Maybe there is a very good story reason, and even if there is not, it not something wrong with the art, just something I was wondering about.
Then I have a small bit of commentary on his position, because with the way he's standing, it looks like he broke his right ankle, or at least badly twisted it. Depending on how he's standing, as I have a bit of trouble finding out because of his complicated (but quite cool) shorts design, Are the upper legs and his hips seen from a side perspective or slightly turned? Depending on that either his upper body or his legs should be turned something like 45 degrees.
Actually giving it a better look, I doubt that position is comfortable. It seems like you had some internal conflict in what of the design you wanted to showcase, and what would position he should be in. If his head were the basic position, his upper body would be in a 45 degree angle, his left leg in a 60, and his right leg in a 90 degree.
I think his left arm is a little too short, and should be extended a little. Especially because his left shoulder should be more visible too. The arm kinda looks dis-attached ones you notice it, it doesn't seem to be attached to any kind of shoulder.
The next thing may come down to my knowledge of the Xenoblade series, so sorry if I critique something that makes sense storywise, but, do the swords have weight? With the way he's running with it it seem like either he's superhumanly strong, or the sword incredibly light? The way he would hold it wouldn't make any sense if the sword had weight and he had the strengt of a human. His hand doesn't seem to grip the sword that well, either. There seems to be a lot of space around the hilt. Did you draw the sword and the character seperate? It also has a slight curve where the hilt is. While the hilt points down, the sword curves up from that point. The sword, as I said earlier already, looks really cool though.
I like the japanese signs, but the rest of the background seems a bit rushed. The drawing that is supposed to match this one has a wonderful background, and these random lines and squibles seem not to fit very well.
I like the design overall, don't get me wrong, I just tried to be thorough with the critique because you seem to be at a point where you know most of the basics, and just need get the hang of some other things, so I really hope this is helpful with picking out the errors and improving your drawing skill. I'm sorry if some parts don't make sense, or if I just straight up forgot words and letters, I'm on a lot of meds right now, and it is noticeable in my writing. If I need to expand on something, or if I was too cryptical, just say so, and I'll try to explain better, haha.