Looking pretty good. I don't have any experience with spirit shamans but the expansions make it much more interesting to me.

For the capstone ability of the spirit warrior prestige class I feel their should be a range of effect by HD for destruction. Otherwise there exists the possiblilty of vanquishing a superpowerful elemental/fey/incorporeal undead with a single move. I would suggest something like creatures with less than 1/2 or 3/4 the HD of the Spirit Warrior are destroyed on a failed save and anything over that instead takes the damage with a save for half damage.