I've given this some thought and watched various theories, and I assume you've read Axle's latest article, so this is what I've come up with:
There is a spirit in the SS that looks vaguely like the blade its self. If you have a look at the pale bloke, he looks like the guilted sword. Both of these blades have some thing to do with a presious thing (a jewl in the SS and gold for the GS) so i think that the spirits inhabit the jewl/metal. I also think that because the wind boomerang in TP has a jewl and a spirit... But thats beside the point. The main thing is, maybe the spirit of the SS knows that it is too weak to banish the evil down below so she takes over the sword by sacrificing herself from it's gem and putting it's power in the actual blade. That makes the sword more powerful and would explain the absence of a spirit in the other games with the master sword in it. This is just my theory but i want to see what you think about it...
There is a spirit in the SS that looks vaguely like the blade its self. If you have a look at the pale bloke, he looks like the guilted sword. Both of these blades have some thing to do with a presious thing (a jewl in the SS and gold for the GS) so i think that the spirits inhabit the jewl/metal. I also think that because the wind boomerang in TP has a jewl and a spirit... But thats beside the point. The main thing is, maybe the spirit of the SS knows that it is too weak to banish the evil down below so she takes over the sword by sacrificing herself from it's gem and putting it's power in the actual blade. That makes the sword more powerful and would explain the absence of a spirit in the other games with the master sword in it. This is just my theory but i want to see what you think about it...