Hmm, I find this conception of pixie confusing.

It's less extreme than a sprite? Are you conceiving of pixies as larger than sprites? I thought the idea was that pixies were even tinier. Even at tiny size, the negatives and positives seem way too close to normal.

Also, the "vulnerabilities" seem a bit random. Why fire metal and cold metal? And there don't seem to be any corresponding positives to cancel out these negatives, though I guess without knowing the xp mod, it's hard to say.

Finally, the name seems a little odd considering all the other races. We have "high-elf," "ogre," "hill-giant" and..."aos-si"? It would seem that "pixie" would much better fit the style of the other races. And "pixie" is a great, evocative word.