The accepted theory is that the Protodermis morphed the Toa into Toa Nuva, created Protodermic Armour and
Tools for them, and transformed their Kanohi into the Kanohi Nuva.
We're not sure if, because they had Golden Kanohi, the combined power made the Kanohi Nuva super-strong, of if it was the Protodermis.
Nor do we know how the other Kanohi Nuva are created.
That's what I say.