As other villainous entities such as the Bohrok and Vahki began to develope around the islands, the Rahkshi knew that they too had to upgrade themselves into more effecient forms. The Rahkshi made themselves bigger but also leaner. Able to perform athletic moves with ease and also sustain massive amounts of damage. This aprticular mdel uses a gas cyclinder to increase the performance of the tubing around it's body. The spines are also set far back as a counterbalance to the heavy chest area which protrudes forwards.
Hmm, love the whole design but I think the upper arms to be made a bit beefier, I know he's supposed to be lean and all, but honestly I got more of "Tank" feel than a "nimble warrior" feel from him. Also, I think the staff's ends could be better, just by adding maybe more armor to them or even giving it bigger blades. To be honest I'm just be nit picky, but I hope I helped. Keep up the great work! :P