According to the history, he as a prince and then king of Dale. And he fought in the war.
Yet, the only trait he posseses is "Dale"...
Why Brand is nor warrior, neither noble?
Oversight most likely. I can't bring to mind others off the top of my head, but Brand isn't alone in missing traits that seem appropriate. Pretty sure there's a minstrel without the minstrel trait somewhere. More of a shame now since traits like warrior and healer may well be getting suppport.
Dain should be noble too, I think. But he isn't.
I could live with that, especially as Noble is very arguable. It may be a bit strange that Thorin (obviously) and Glóin and Gimli only of all the Dwarves are Noble but I it is indeed harder to argue why Rivendell Minstrel is not a Minstrel, or even why Vilya and Nenya are not items whilst Ring of Barahir and especially The One Ring are.