The Kanohi Faxon was the Mask of Kindred.1, 2
Notes
The Kanohi Faxon, the Mask of Kindred, allowed Hahli to take on the abilities of other sea creatures.3
The Great Kanohi Faxon allowed its user to simulate the powers of creatures who shared the same environment. In Toa Mahri Hahli's case, she used it to duplicate the powers of certain sea beasts.1
The Kanohi Faxon, the Mask of Kindred, allowed Hahli to duplicate the powers of sea creatures.4
For a being with the ability to fly, the Mask of Kindred would allow its user to duplicate the powers of every other flying creature.5
Kindred referred to beings or creatures who were related in some way. In the case of the mask, it referred to the user's environment and how they operated within it. A being that could fly could use the mask to give them any power other flying creatures had. This happened regardless of whether the mask user was close to these creatures or not, they were still kindred.6
The Mask of Kindred was limited to copying one ability at a time.7
The Mask of Kindred could not duplicate mask powers or any other powers of Matoran, Toa, or Turaga. It was meant to duplicate Rahi powers.8
A Toa of the same element as one of the Inika couldn't duplicate their lightning powers or antidermis immunity because the mask copied Rahi powers, not the powers of other Toa.9
It's debatable whether a creature that could survive in lava could be considered kindred to a Toa of Fire, as the creature may be on a higher level of fire power.10
It's debatable whether a Toa of Water could share a fish's ability to breathe underwater if the Toa breathed air and lived on land.11
The Mask of Kindred was a Great Mask. Like most masks, how powerful it was depended on the user. If a user knew nothing about Rahi and had no imagination, it would be useless because it wouldn't pick powers to use for its wearer.12
Powers granted by the Mask of Kindred were only temporary. It's uncertain whether something that would be outright physically impossible for the user to do, such as setting themselves on fire, would be a power they could duplicate.13
A Mask of Kindred user didn't have to touch the Rahi to copy their powers.14
Ehlek's abilities could not be duplicated by the Mask of Kindred because he wasn't a Rahi.15
If one of the Barraki used the Faxon, their kindred would include any sea creature, not just the ones they resembled.16
All of the Mahri were water breathers, so they were kindred to all other water breathers as a result.17