Well, I definitely have to say that this is the best MOC I’ve seen from you so far.
As to the MOC itself, the gear function is nice, but sticks out a little bit too much - perhaps you could put the smaller gears that connect to the arms below the bigger gears instead of above them? This probably would also fix the arms seeming so short.
Alos those shoulderpads would probably look better if properly aligned.
As to the pictures: Could you try getting them all as sharp as the one you took of the gear mechanism? Perhaps it helps if you take them upright instead of broad. Better lighting would perhaps help, too - maybe try taking pictures outside?
And the story:
His assigned region should be “none”, since Destral is the assigned region of the Brotherhood’s leader. Hau is the Great Mask of Shielding, not Fire. Kolhii was invented by Onewa and Whenua on the island of Mata Nui if I remember correctly. Also the Barraki didn’t attack Destral.
In general I feel like the “inventor of sports” role might be a little difficult to make believable, since the the only sports that are canon are Akilini which was invented by Kodan, Kolhii, which was invented by Onewa and Whenua and - if you want to call it a sport - the gladiator fights on Stelt.
The idea of a Makuta who actually liked to make others happy is interesting, but you should try to find another, more plausible way for this in my opinion.
Oh yeah, and a Matoran rebellion at this time doesn’t really fit in either. In addition I just can’t see a Makuta being killed by Matoran. It just doesn’t work for me. And if he is a nice guy with many friends - why would someone even want to hurt him?
Sorry, but I also highly doubt that Destral ever was fun for anyone.
I could try to think of something using Wanitama’s personality in a better and more plausibel way tomorrow, if you like.
Otherwise I would be curious what @pizzacheetah and @21sselliW think about the backstory and its current potential. It’s a very original one but I can’t really see a way for it to work as it is now.