Yeah it took me awhile to figure out. You need to somehow push up the shoulder as much as possible while keeping the arm straight and level, while angling down the wrist. And then at the same time you also have to get the other arm positioned right. And the outfit is fighting you the entire time.
Only bummer is you can't use the light up arm with this pose.
Thanks for the advice. Started working on it again and i'm getting there... i think. I believed i could make it work with the tunic on but it really helps removing it so shoulder articulation is showing more. Hopefully, i can put the tunic back on without too much difficulty when i'm happy with the result.