I think during the podcast, there’s complications between these two raahkshi. In summary, we’re giving the right powers to the wrong Raahkshi.
It would make much more sense to give the power of gravity to the air Raahkshi. Not only because of relevance to the element, it could also symbolize what he wants to do with the Kanae government; bring them down to his level (an orphan) through whatever means necessary, even if it means murder.
For the water Raahkshi, giving her(?) the power of poison would also relate to the element (poisoning water supply), but it could also work on irony. I say keep the Aqua-Man-esque motivation that Naho should separate itself even further from the island, but pay more attention to why. Maybe she could be a little crazy even before becoming Raahkshi, and she’s paranoid that the other regions will lead Naho wayward, poisoning its morals, while in reality, she’s the one poisoning the rest of the island.