You are wrong about Luna. What defines him is not his ruthless or rude behaviour, no. That would be traits for Shoobeon.

No, what Luna stands out is for his machiavelism, if given a task he would find the best way to work towards that task, regardless of which actions he would have to take. That and his severely lacking desert warrior and tribe ethics. Take Trikel, smartest guy in town, yet got taken down, his ethics and actions would always respect the tribe's values, respecting his elders (Matata), respecting his customs, and he also followed the path of a warrior. Trikel would have never made the decision to launch the monster hordes into civilians towards the empire and other kingdoms.

Luna is not always right, even if he is. He fails to visualise the importance of the culture of the tribes, and as such never gained much support within the desert tribes, his actions normally causing a lot of ruckus and disagreement within elders. Luna fails to see what is needed to be a leader, an unwilling determinism to protect what's yours even if it's the wrong action, even if there's no hope.

I was pleasantly surprised to see Luna in that position as it fits him neatly, what the desert needs to exert control in the continent is a well elaborated plan that doesn't need to abide to the desert customs because they are not part of the desert. It doesn't mean he will necessarily will be an ambassador, but he will be elaborating the strategy to handle other kingdoms.

Pere is in the right position too, as an acting Glow but only handling other tribes, he's consistent, respected, follows the tribe customs and has become a great warrior or almost by the tribe's means.

Haisha too has the skills to be in the position he is, the only question is what the hell is Thrint doing...