Toa greis is not just any toa, he is a prototype. Long ago when the great beings were experimenting with the creation of the toa, toa greis was the 5th prototype out of 10. He can speak the language of the great beings, and he is mostly a machine, but he has some organic features to him.
A full view of him
A close up on his upperbody
His arm, nothing new
His legs, lower legs are new
His lower body
Another view of his legs
His back
The back of his legs
His energy scythe, I know soon to be upgraded, he is sortof just a prototype of himself