The novel itself contained a shapeshifter character, who I believe had violet or purple eyes, might have been female, might have been an assassin. I believe the character was not the protagonist or antagonist, but a side character that the main character wasn't sure they could trust. I also believe the shapeshifter character was from a race of desert people. I do know there was a female character, but not sure if she was the shapeshifter, the main character, or another character altogether. I don't really remember the plot much beyond that.
The cover I believe featured a kind of desert scene with one of the characters, and for some reason they kind of reminded me of Elfquest looking people, but not sure if any of the characters were elves.
I remembered a new plot point. the story involved magical weaving, like time weaving or reality weaving.
I thought of this while looking up Tamora Pierce, but I don't think it was that novel, also that possibly the main character was from Earth or something and transported to this fantasy world by the magical weaver character, at some point one of the characters has to learn to use the loom or whatever it's called with the threads of fate and weave their color or someone else's back into existence.