It can't because dwarves have the same special powers, not arnor and Gondor... But if you want, someone have made a mod that allows you to play arnor instead of Gondor when you start the game
I've also made a new model for farms, based on the sixth building of laketown (bfme models)
EDIT: Alternative for the arnor symbol
and arnor fortress wall (for fornost for exemple)
arnorian new models
Black=basical unit
Red=Arthedain unit
Green=Cardolan unit
Blue=Rhudaur unit
arnorian captains (instead the banners)
Gondorians in heavy armor