Silver Kanohi

The same way six different Great Kanohi can be trade for one Golden Kanohi, three can be traded for one Silver. It is probable that two Silver Kanohi with no common power could be trade for one silver Kanohi. The Rua looked like a Silver Kanohi.

It is most likely that two Silver Kanohi with different powers could be traded for one Golden Kanohi.