First of all, great picture, I hope to also incorporate 3D into my work at some point in the future. Regarding the poses, it is possible to have them be both welcoming and protecting.

Google images of the Christo Redentor in Rio Dejaneiro and how they have his palms open facing forward. If you bent the elbows then it would seem more relaxed, but like you intuited naturally you want a more rigid pose if they're a protector. That's why I think the pose of the Christo Redentor is a good starting point.

Keep up the good work!