I quickly looked up Reptile, Bird, and Mammal eye color and found many pictures of blue eyes available on the internet. So based upon that I would say that this would not be rare in the game of SHARD in the least. It all depends upon how you wish this to manifest in the fiction of your game. If for example you wanted to gain a benefit from having rare colored eyes you would need to purchase them as an Asset... on the other hand if you wanted to have this manifest as a negative trait you could speak to the game master about it being a Drawback... There are many different cultures upon the world of the false dawn and the opinions and values of each may differ widely.