Its not so much that FE13's artist did bad artwork, his artwork is of a very high quality, its just that a lot of the designs he did were dumb for several of the classes, and a lot of the designs he did were rather tasteless (as I think Diddy or Frost pointed out, why are a lot of the women bending over?).
Also, the artwork of Galzus you posted was not done by the official artist for FE5. Here is the artwork he did for him:
Okay, I googled the character you mentioned, and the funny thing is that Alvis looks even more similar to that character in the original artwork released for FE4 back in 1996: